First guide! Bear with me.

Yes, I'm aware there are multiple types of runes. This will be explained in the "Runes:" section at the bottom.

Basically, this is a slow build at the start (as you only have AP from your runes), but quickly picks up power as you get deeper into the build. Early on, you should play Vlad just to harrass the other lane. It's recommended that you go to the Middle lane, since it would be easier to harass one person, rather than two, as well as the fact that Vlad is an amazing carry late game. Basically with boots, you can run to the edge of your Transfusion range, hit the enemy, and run back behind your minions. You can use this technique until you feel comfortable in the fact that you can secure a kill. Later in the game, with this build, you should be able to easily solo atleast two of the enemy champions by yourself (if they arent super fed, anyway), and be able to turn the tide of a teamfight into your favor (especially with your R, since it lets ANY attack do amplified damage for the duration). A useful trick to note on vlad is that your W can block ANY missle. This includes basic attacks (if you W fast enough), Karthus' Ultimate, Ashe's arrows etc. Your E is your secondary attack, if your Q is not up. The more stacks it has, the more damage it will do, but you can really only spam it when you have Spellvamp.

-Disclaimer-
This guide is generally meant for Normal games, which is why there is a mejai's. In my opinion, there should be no cookie-cutter guide to ANY character -- buy items as the situation demands. You will learn this in time with Vlad, as with any other character, so this guide is just a starter.

Start with Boots of Speed and 3 Health Potions. This is pretty self explanatory. The Boots are for harassing (as previously stated), and the health potions are for laning longer (I also use them when i'm about to towerdive, if I feel like I need an extra bit of health).

When you go back, preferably with one kill, buy a Hextech Revolver. This item will let you spam your E from now on, since you'll be healed by doing it on a minion wave. Also, your Q will give you about 150% health compared to before. The next time you go back, you should finish building a Will of the ancients. The spellvamp allows you to lane for forever, as well as allowing you to solo atleast two of the enemy team's champions. After you go back, buy Sorcerer's Shoes and a Mejai's if you're confident, if not then read below.

Next on your list is a Rylai's Crystal Scepter. This gives you a decent bit of health and AP, letting you be a bit more tanky (but not a real tank since you cant draw aggro in team fights, or live down a 5 champion burst most of the time), as well as giving you the ability to slow down enemy champions. This is one of the most useful tricks in the game, because with your damage, and the enemy not being able to run away, you're basically guaranteed kills. No more will be the day that you ALMOST got a kill, but they ran away, because now they're slowed down and you can capture them! If you didn't get a Mejai's, then at this point you should buy a banshee's veil. It's a very good all around item, giving Health, Magic Resist, and a Spell Shield.

Next, a Spirit Visage. This item's good for being a bit more tanky because of the health / MR, but he most important part is the passive. The passive will give you more survivability, which is VERY important, especially since Vlad has 2 abilities that this would affect. Your Transfusion will now give you 400+ health back (because of the spell vamp and the abilities health gain put together), as well as ripping chunks off of the enemies health bar.

Lastly, Vlad needs a Rabadons. This is a good item on EVERY caster, because of it's passive, and it's a pretty obvious choice to get. By the time you buy this, you should have about 700 AP, at least 4000 HP, and a decent bit of MR. All in all, you should be a VERY tanky, VERY powerful carry. Once you get this item, the rivers will run RED.

If the game drags on even after you get the Rabadons, or you just want to overkill the enemy, buy the elixir's after you get a rabadons. These will give you a little bit of extra stats, and they're pretty cheap at this point in the game.

Alternate Items:
If you decide not to get a Mejai's, there are a few alternate items that work VERY well on vlad. If you feel like you're dieing to quickly to spells, then a FoN or a Banshee's will work superbly. If they've got an AD carry that's murdering you, a Randuins is a GREAT item, since it will give you armor, hp, and hp5. All of these work very well on vlad, as well as the other effects of randuins (cdr, slowing enemies, etc). An item that I believe is NOT good, though, is a Warmogs. It's only good if you're murdering them, and they dont do much dmg to you, but do a LOT of attacks. Since this will probably not happen, as the enemy will have a fed carry as well, it's just not a viable option. It's only decent if you need extra damage, but there are other items that can fill this spot much easier (Lichbane for dmg and some resistance against magic, Zhonya's for damage and resistance against attack damage).

Since the guide came out, there have been a few changes to Vlad. Basically his Q heal has been VERY lightly nerfed, almost unnoticable except at the very beginnning of the game. There should be no real change in play style, though, since he still has his incredible burst and his heal is only SLIGHTLY lowered (About 5 health less per transfusion). Same playstyle, slightly less survivability early game, same amazing late game.

Rylai's now counts Vlad's Transfusion (Q) as a single target spell, so it now procs the 30% slow rather than the 15% slow. Good buff here because you can chase more easily.

Blue Cooldowns. Flat so that you can Q more at the beginning. Rising may be better late game, but you shouldnt NEED them that late in the game (especially if you get your mejais to 20 stacks). Another very good option is Blue flat AP. They help out a lot early game, for obvious reasons.

Yellow for Health / AP. Health if you feel like you're not surviving enough, AP if you want to be more powerful early game. These are very important, since they're one of your main forms of extra damage at the start.

Red for Magic Pen. Same explanation as the Sorc Boots, but you get these at the start. Also, probably the single most important rune when first starting vlad, since it'll give you the most damage at the start.

Purple for AP / Health. Same reason as the Yellows basically. Another VERY good option that I like are Movespeed quints. They don't make you as strong or give you more survivability early, but they're GREAT for harassing. I recommend using HP at first, AP when you're more comfortable, and Movespeed when you think you're REALLY good at vlad.

I go with Flash and Ignite.

Flash-In a teamfight you can R and then jump in w/ E and W. You can run away with flash, you can get to a running enemy and secure a kill, dodge a skillshot if you're on the brink of death (such as Ezreal's R, or Ashe's R). All in all, a very useful skill.

Ignite-Kill secure, Mundo killer, Anti-Vlad. Very useful skill indeed.

Alternates:
Really the only good alternates would be:

Ghost-Running to catch up or escape from an enemy.

Teleport-So you can B when needed early game and get back without letting your tower die, help a minion push, etc.