This is one of there multi question post cocerning someone who hasn't started a warhammer army so without anymore explaining here are my questions:

1. Which bloodline should i go for? if so what are the reasons?

2. same as above but if not a bloodline could i be able to do a normal undead force?

3. Starting an army what should i buy i know i would probarbly need some heroes such as a necromancer and a vampire but what box sets should i go for or should i go for a starter deal?

thank you for your time

For bloodlines, take the one that apeal to you the most. The one i suggest to you is Blood dragon, Strigoi or Necrach because they are amongst the easyiest to play.

You could do a all necro army, it would be good and not to hard but they can cost a lot(youll be summoning a lot)

for the boxed set, im not sure

For the boxes, I say go with one of each of the plastics. Maybe get another one or so for raising with your necromancers. For bloodlines, I would go with the one with the coolest models or the one with your favourite bloodline powers.

For bloodline, just get whichever one suits the playing style that you think you'll use.
Necrarch for magic heavy and lots of dead raising.
Blood Dragon for taking on other lords.
Strigoi I'm not too sure about, but I think their good against monstrous think like trolls.
Carstein is good all around.
Lahmia might be fun to play because you can mess around with enemy leadership.

the two i prefer is the Necrach for their magic and the blood Dragons as they have the coolest models

As Khrangar told you, pick about 2 boxes of skeleton and zombies. Pick a Hero and some necro. Play a little with it and then you can had what you feel you want to have(ex: more skeleton, more summonable, grave guard, etc)

Here's what am planning of buying (may change) Vampire (any bloodline) because you get one mounted and one on foot, Necromancer blister ( same again) 2 boxes of Skeletons, 2 boxes of Zombies, several blister of Grave guard (full command), Dire wolves and mail ordering several parts and pieces to make several zombies/ Skeletons without having to buy another box set.

but heres what i am prob going to do though instead of the 2 necromancers am going to order 2 on foot one to be placed in a unit while the other is by himself, with the vampires one inside with the grave guard (on foot) while am going to save up for several black knights for the other one but till then he's on his own :)

Which brings me to my next point is a Vampire count (blood dragon )mounted on a winged nightmare worth it? or is he better on a zombie dragon?

hmmm, hard to choose but i prefer having my vamp in a foot unit or in cavalry
the best one seems to be the zombie dragon, while the nightmare is less costy and good on charge

Unless you are going for a highly mobile force with lots of dire wolves and black knights, its really best to keep your Count on foot with the troops. He's going to be your general, and you want him where he can make the greatest number of troops march, not flying off somewhere where he can get picked off by a cannon, causing your army to crumble around you.....

Just my opinion.

Cheers,
DLJ