Muktol

*like*
If you are playing paper-pauper (which is basicaly every common card can be used) you could add "Ancient Den" (Banned in Modern) and "Darksteel Citadel" to increase the number of artifacs you play.
With 4 copies of "Glint Hawk" in the deck I would raise the number of "Ichor Wellspring" as it enables you to cast it again, and draw another card.

"Bonesplitter" and "Leonin Scimitar" could be interesting artifacts for this deck, maybe "Horned Helm" as provides trample to the equipped creature.

Greetings
Muktol

With acces to black I would change from "Shrine of Loyal Legions" to "Blood Artist". It's no artifact, though it can help you to defeat your opponent and 'doubles' the lifegain/sac.
I would perhaps splash green, remove the Keyrunes and add some defender-ramp (Axebane Guardian, Overgrown Battlement, Wall of Vines/ Carven Caryatid) to get the 5 mana you need to go infinite rather fast.
Otherwise I would at last remove the white-splash (1 card which has to be removed) to make your manabase more stable; maybe add some search lands.

Greetings
Muktol

Single or multiplayer-deck/ games?

Some changes I would do:
Concentrate on 1-2 finishers. 4 big one-offs seem a little bit to much for me.
Remove "Demon's Horn", this belongs more into a midgame-deck, the lifegain is rather low (and irrelevant) on aggro decks.
Remove "Basilica Screecher", there are better vampires.
Reduce the number of "Bloodline Keeper" by 1-2, and add "Vampire Nocturnus" instead. Gives your vampires a nice boost and, what is more important, evasion.
Add 1-2 "Gatekeeper of Malakir", removal on 2 legs and chumpblocker
Sideboard "Vampire Hexmage", 2/1 first strike is not bad, but I would use this one mainly to go after your opponents planeswalkers.

If you want to use the combo "Exquisite Blood" and "Sanguine Bond", I would reccomend using both 1-2 times, but using some tutors, to get the cards in your hands.
Sideboard "Crypt Incursion", normaly you don't need to empty your opponents gravexard every game.
Replace "Sorin's Thirst" by any other point removal spell.
Change from "Exsanguinate" to "Consume Spirit", this spell can also aim at creatures and thus gives you another removal.
"Feast of Blood", if you feel that you're having troubles plaing this spell because your opponent tends to remove yor creatures, change to any other good point removal spell (e.g. "Doom Blade", "Go for the Throat")
Remove "Sorin's Vengeance", comes far too late and is rather a overkill then.

Greetings
Muktol

I would remove/ replace some creatures here to add some removal and draw-spells
"Bloodcrazed Neonate" could be replaced with "Bloodghast"
"Erdwal Ripper" cc3 for a 2/1, even with haste, is too weak. You could try "Markov Blademaster" though I would also remove this one, as he is also too slow, and needs to much support
"Typhoid Rats" a 1/1 dteahtouch is nice, but won't benefit from vampire buffs. If you want a black cc1 drop, try "Vampire Lacerator" or "Pulse Tracker"

Greetings
Muktol

I would take a look at "Carven Caryatid" ({1}{G}{G}; 2/5; defender, When Carven Caryatid comes into play, draw a card) instead of "Sylvan Caryatid". It costs one more mana to play, but enables you to kill X/2 creatures from your opponent and, what is more important to me, lets you draw a card.
You could also think about sideboarding "Fog" to add some additional defenders or spells. Furthermore 4 "Jace, Memory Adept" seem a little too much to me, normaly you play permanents which count as legendery only 2-3 times.

Greetings
Muktol

You have to decide if you want to play mill, or U/B control, or something else. But mixing those strategys won't do you good.

If you want to continue with mill, I'm missing some of the best millspells there are in U/B:
Dream Twist, Breaking // Entering, Glimpse the Unthinkable, Mind Funeral, Mind Sculpt
Noxious Revival/ Snapcaster Mage
Surgical Extraction

Sample mill-deck from wickeddarkman: http://www.mtgvault.com/wickeddarkman/decks/fast-reliable-modern-mill/

Greetings
Muktol

The I would see that my deck has enough removal/ control spells, some carddraw, some creatures which help to protect you, and 1-2 finishers which will then defeat your opponent.

Either use "Argentum Armor" or "Grappling Hook" as equipment for your finisher
Sideboard "Elixir of Immortality" against mill/ discard
"Feast of Blood", if you feel that it's hard to activate this as you opponent removes many of your creatures, change to another point-removal spell.

-1 "Ring of Valkas", you will have more black creatures in here than red, and this one is only useful if used early
-1 "Staff of the Death Magus", to expensive with too little effect
-1 "Veinfire Borderpost", mana-fixers won't be needed
-1 "Anowon, the Ruin Sage", to expensive with too little effect
-1 "Butcher of Malakir", to expensive with too little effect
-3 "Rakish Heir", you will stay more defensive at the beginning, and your finishers should be able to do the job without support. If you want a alternative to this, try "Curse of Stalked Prey"
-1 "Unhallowed Pact", though good and cheaper than "Painful Quandary" I wouldn't use it because it can't finish the game itself.
-2 "Auger Spree", there are better point removals
-1 "Grim Return", you will remove the big threads in your opponents hand by discard, and only the small creatures by removal, so this will be too expensive to play.
-2 "Diabolic Tutor", you will get 8-10 finisher cards, so you shoudn't need a tutor
-1 "Disturbed Burial", not modern legal

+ 1-2 "Blade of the Bloodchief", good to strengthen your early defenders and utility creatures.
+2-3 "Ring of Xathrid", good to strengthen your early defenders and utility creatures.
+ 2-3 "Gatekeeper of Malakir", 'point removal' (your opponent can decide what he sacs) and blocker.
+ 1-2 "Guul Draz Assassin", good, but a little expensive (cc1+ cc4 for the first effect), removal on 2 legs.
+1-2 "Stromkirk Captain", buffs all your vampires and gives them first strike.
+2-3 "Painful Quandary", expensive but good finisher. Either your opponent cripples his hand further or looses life.

Some suggestions I would think about adding to this deck:
Duress/ Thoughtseize/ Inquisition of Kozilek, Extirpate/ Surgical Extraction
Dismember/ Go for the Throat/ Lightning Bolt/ Terminate/ Dreadbore
Sign in Blood/ Read the Bones
Ghost Quarter
Vampire Nocturnus (Depends on how many non-black cards you will have), Bloodlord of Vaasgoth, Bloodline Keeper

Decide for yourself which creature(s) you want to use as finisher: "Drana, Kalastria Bloodchief", "Falkenrath Marauders", Necropolis Regent"

I would increase the number of lands to 22 or even 24, and add some searchlands. Depends on how the colors are distributed.

Links to two of my own vampire decks (B/R aggro and B/W pauper sacrifice)
http://www.mtgvault.com/muktol/decks/br-tribal-vampire/
http://www.mtgvault.com/muktol/decks/bw-paupervampire-sacrificing/

Greetings
Muktol

That would be standard , and there are not many (good) vampires in this legality. The next one would be extended or modern.
So, do you want to play this deck fast (aggro) or slow and more controlish (midgam)?

Some tipps and suggestions, based on my monoW equipment deck (http://www.mtgvault.com/muktol/decks/monow-kor-equipment/)
As you have a rather low mana-curve, you could try to reduce the number of land by 1-3.
I would definitly reduce the number of creatures and add some more to ensure you have enough of them to equip the creatures you have on the battlefield.

Suggestions:
Auriok Glaivemaster ({W}; 1/1; As long as Auriok Glaivemaster is equipped, it gets +1/+1 and has first strike), Etched Champion ({3}; 2/2; Metalcraft -- Etched Champion has protection from all colors as long as you control three or more artifacts), Goblin Gaveleer ({R}; 1/1; trample; Goblin Gaveleer gets +2/+0 for each Equipment attached to it)
Basilisk Collar ({1}; {2} to equip; creature gets deathtouch and lifelink), Bone Saw ({0}; {1} to equip; creature gets +1/+0), Bonesplitter ({1}; {1} to equip, creature gets +2/+0), Cranial Plating ({2}; {1} to equip; creature gets +1/+0 for each artifact you control) Swiftfoot Boots ({2}; {1} to equip; creature gets hexproof and haste)

Greetings
Muktol

Depends on how you want to play this. Vampire decks normaly try to be fast as hell (I have seen a single deck that was built for midgame-tactics) and if you wnt to do so, you can remove some spells.
Second question would be the legality. As you didn't tag any legality I assume that you want to play either kitchen table (where legality is no big mather) or modern.

Greetings
Muktol

Some alternatives:
"Liliana's Caress" against "Megrim"...cheaper to play and the life-loss can't be prevented
"The Rack" against "Shrieking Affliction"...The Rack activates it's ability a little easier and perhaps more often
"Smallpox" against "Mental Agony"...Smallpox attacks all recourses you and your opponent have: mana, life, cards and creatures. The only thing of these which might hurt you a little bit is the own discard. If you don't want to use Smallpox, I would nevertheless remove Mental Agony, as it is rather expensive to play, and maximize some other slots .

"Scepter of Fugue" could be an interesting Artifact for you, as it enables you to remove a handcard from your opponent every turn, no matter what cards you have on your hand.

Greetings
Muktol

Where's the fun on winning all the time without any effort ;)

On the one hand, the Gatekeeper is hard to support (especially with your manabase) as in 99% of the times you want to cast him he needs triple {B}.
On the other hand he benefits from beeing a vampire ("Stromkirk Captain" and "Vampire Nocturnus") and can even remove rexproof or indestructible creatures (when they are alone on the field, otherwise it's your opponents choice)
"Ash Zealot" is a human and doesn't benefit from the vampire buffs. He also works only if someone casts anything from the graveyard (flashback, unearth, and so on) so if this happens rather often in your matches he is at last work sideboarding, if not, stay with the Gatekeeper. If you want to replace him with an aggro creature, I would tend to use "Bloodghast"

I know the drawback on life isn't that big in this deck but it's one of the few creatures I don't like here. You could perhaps take a look at "Bloodghast" (can't block, comes again from grave with landfall)
If you want to dig a little deeper with carddraw, try "Read the Bones" ({2}{1}, pay 2 life; scry 2 then draw 2 cards) instead of "Sign in Blood"

Mouth (/ fingers) faster than Brain -> If I get the chance to do some testgames, I will give 1-2 Purphoros, "God of the Forge" and 2-3 "Nykthos, Shrine to Nyx" a try.

A very simple (and silly) one: I don't have any free slots, and I don't know what I could remove to make some space for it ;)
As for "Nykthos, Shrine to Nyx", I think I won't need ramp in any form. The mana-costs are very low ("Siege-Gang Commander" is not supposed to be hardcast but brought into play with "Warren Instaigator") and even if it doesn't look like that, I work a great deal with tokens here (My opponents tend to shoot many goblins down, dont know why *g*) and those don't count towards devotion (cc0). I also don't have any 'pay X, deal X damage' spells in here.
"Purphoros, God of the Forge" is a nice card, could also give me another winoption, but it has the same mana-costs as Krenko, and furthermore, does nothing if he is alone on the field. I could try to replace "Furystroke Giant" with it, but that would require some test-games, I don't have the time for at the moment :(

I use defender-ramp in my G/W angel deck (http://www.mtgvault.com/muktol/decks/wg-tribal-angel/)
"Axebane Guardian", "Overgrown Battlement" provide mana and "Perimeter Captain" helps to stay alive against aggro.

If you want to add this 'engine' I would do the following changes:
-2 Cultivate
-2 Rampant Growth
-2 Scouting Trek
-3 Knight of the White Orchid
-3 Gatecreeper Vine (You don't use any gates, and there are better defenders)
-2 Seraph of Dawn
Sideboard 3 "Solemn Offering"
= -17

+4 Axebane Guardian
+4 Order of the Stars (Or any other good cc1 defender)
+4 Overgrown Battlement
+4 Perimeter Captain
=+16

With the free slots I would fill up either "Ajani's Pridemate" or some other spells you use.
Furthermore, I would change to some duallands and, if the defender ramp works, you could try to reduce the number of lands to 20.

Greetings
Muktol

*like*
In my B/W pauper vampire deck (http://www.mtgvault.com/muktol/decks/bw-paupervampire-sacrificing/) I use humans to buff up "Falkenrath Torturer". For me "Driver of the Dead" has shown it's value there, as he can bring creatures back from the grave to the battlefield (and not like "Disentomb" only onto your hand) and then can also be sacrificed.
Personaly I like to place +1/+1 counters rather than buff the creature up, so I use "Bloodflow Connoisseur" as second sac-outlet. I think that this might also work for your plan, as it looks to me that you want to stay defensive and defeat your opponents with "Blood Artist" / "Kalastria Highborn". Thus "Vampire Lacerator" also could be replaced with e.g. "Butcher Ghoul"; cc2 vs cc1, I know, but the undying could serve you well.

At last, I would take a look at cheap hexproofe equipments, to give your key-creatures some protection, e.g. "Swiftfoot Boots"

I hope I was able to give you some ideas
Greetings
Muktol

I would try to reduce the number of different creatures but to increase the quantity of the remaining ones. The expensive angels could stay in as 1- or 2-offs, but you will need a good base to defend yourself until you can play them.
My own angel deck is based on G/W and utilizes defender-ramp to get the mana I need (I am able to play any angel I want to with turn 4)

Greetings
Muktol