No worries, because Vlad makes a totally sub-par tank. But typically that's better than having none at all. Vlad can initiate with Hemoplague, gets a little AP from his health with his awesome passive, and can get out of sticky situations with Sanguine.
Masteries are 9/21/0. I love that 15% spell pen those 9 masteries in Offense can give you. And of course, Ardor because you're tanking.
Runes: MPen Marks, HP/Lv Seals, AP/Lv Glyphs, HP Quints. Looks familiar, eh?
With tank Vlad I like to start out with Warmog's. Call me crazy, but I've been a Warmogs fan since forever. If you don't like it, get something else.
The massive HP will give Vlad some pretty good AP. More than 50 AP when the Warmog's is maxed out. If you don't like Warmog's, get a Leviathan.
Merc's treads usually, if they have no CC go swiftness.
Mostly magic? Banshee's. Mostly AD? Sunfire. Typical stuff. Both have health, Vlad's favorite stat.
Get a Guardian Angel at this point. It's just too great.
Now, it's time to follow your tanky instincts. If you bought a Sunfire but they also have a mage giving you trouble, get that banshee's. If not, get another sunfire, or a thornmail, or whathaveyou. And vice versa.
If you ever decide you're tanky enough, get a Rylai's or a Zhonya's. Otherwise it's business as usual.
Stay tuned for more Vlad goodness!