The deck isn't a bad build at all. It looks like an aggro deck so I do see some areas that it can be covered in;
Creatures- It might be best if you take out the
sin prodder. Reason being, it lets your opponent say no to your good cards that sometimes they will desperately say no to just so you can't have them.
Olivia's bloodsworn,
indulgent aristocrat, and even
twins of maurer estate would be good choices.
Olivia's bloodsworn can make your vamps hit faster. The aristocrat can make you other creatures bigger. This can also be done by playing
malevolent whispers and then sacrificing the enemy's creature. That or sac the tokens you make when playing
call the bloodline. And lastly the twins are a 3/5 for basically 3 mana, that's a pretty good trade off.
Spells- You have good spells but if you main or even side board cards that mess with the opponent such as
pick the brain,
vessel of malignity, even
magmatic chasm so they can't block. Building a strong deck is one thing, but keep in mind that your deck has to beat someone else's. If you know blue is a
weakness for this deck, add something such as
elusive tormentor who can make himself hexproof. Just try ideas such as these and you might see some improvement as far as the deck build goes.