He doesn't function as a jungler (can't clear), ADC (no AD scaling, abilities have cast times), or support (little utility, gold + level reliant). I would only recommend playing him top lane or mid lane.
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Typically you want Sorcerer Shoes against squishy teams (for higher burst), Ionian Boots against tanky teams (for higher DPS), or Mercury Treads against teams with a lot of CC (for tenacity and survivability).
Important items:
Core items. Your sustain with either item is fantastic and can allow you to easily wear down your opponents with constant healing and harass. Also allows you to keep your E stacked more easily without sacrificing health. Don't bother with Hextech Gunblade; it's more expensive and you don't actually use the AD or lifesteal.
is great for stalling, avoiding damage and CC, and durability. A common rush against AD opponents (after Revolver).
is fantastic for kiting and chasing opponents and provides a lot of durability and damage (double-dipping with Crimson Pact).
is nice for wearing down tanky teams when combined with Rylai's Crystal Scepter. Haunting Guise can give a nice power-spike early if snowballing and this is useful for sustained damage later in the game. Not a core item, but it has its place.
provides a massive amount of damage and health after you have a couple items. You pretty much always want this at some point but you don't usually rush it.
allows you to penetrate magic resistance and can be necessary to kill tanks in a timely manner. Even if the enemy team is full of squishies, it's still a nice power boots.
are nice situation purchases against magic-damage heavy champions or teams. They are somewhat low on damage compared to other options, but they can work in the right situation.
provides a lot of movement speed and more burst at the expense of not providing defensive stats. It's a viable option if you need the movement speed or burst damage, but there may be better options.
Movement speed is crucial on Vladimir since you have no CC to kite or chase. For this reason, Movement Speed quints are quite powerful on Vladimir.
Similarly, Vladimir scales great with CDR but can't always itemize it. If you can get away without the early MR, Scaling CDR Glyphs are a good pickup.
When laning, focus on CS early. Vladimir can't really fight most other champions early, so focus on last hitting with autoattacks.
If possible, try to save your Q to poke your opponent early-game. It has a long cooldown and it's your only way to actually fight most opponents.
Try to stay back so that your enemy has to enter your minion wave to trade with you. Your minions will deal significantly more damage than you can put out.
Once you have level 9 and Hextech Revolver, you can take a tower shot to harass your opponent with EQ while keeping your health up. You have a lot of sustain, so focus on wearing your opponent down while they are trying to CS under tower.
Vlad often pushes the lane, so Greater Stealth Totem can be quite useful to prevent yourself from ganks.
You typically want to take 21/9/0 masteries.
Your summoner spells are typically a combination of two of Teleport, Ignite, Flash, and Ghost. Any combination of those options (except Ignite and Teleport) works quite well.
Your main options for starting items are Boots of Speed, Cloth Armor, and Doran's Shield. Amplifying Tome is quite risky since it doesn't provide much sustain.
While you have sustain from your Q, you can't use that when zoned from creeps. Take a couple health potions to lane to heal up after bad trades if you are zoned.
Krugs (and less favourably Gromp) can be used as a quick source of healing during laning phase. Just Q them at max range and run back to heal off of them.
Vladimir can't do a jungle camp at level one. If your opponent is doing a camp at level one, intercept their minion wave before they meet with yours and then run into the bush after they each attack you. When the minion waves meet, one of your creeps should be focused down immediately and the wave will push to you. This prevents you from overextending and ensures your opponent misses many minions when they finally get to lane.
WingsOfDeath used to play Vladimir quite a bit and his Youtube videos might be a good reference.
does apply to his spells.
Mid lane normally you want a heavy AP items.
While top lane you want AP tanky 
x2 in my life because its annoying and takes forever to kill you even if you dont get the mana bonus on it, or the stack on valor passive its still great for SUPER TANK SUPER TANK HE'S SUPER TANKY!
