By using the 7 flat damage mark runes and the 3 damage bonus from masteries, you will have enough damage to activate your passive from level one. You will also have more than enough abilitypower from runes and masteries to activate the other part of the passive.

Since you have both parts of the passive activated in level 1, I find it a good choice to start with boots. This is to be able to harras and dodge enemies easier.

You should try to rush an Hextech Revolver as soon as possible. As soon as you have this, you will have an incredible burst damage when using your q. And also have enough spell vamp to stay in lane for as long as you want.

The next thing you should do is decide to finish boots, or go for Sheen. If you play against champions with abilities that is hard to dodge, you should go for boots. If you don't, Sheen is the best pick, as it gives you an even more incredible damage output.

When you've bought Hextech Revolver, Sheen and tier 2 boots, it's time to get some survivability. For this, i usually build Rylai's Crystal Scepter, because it gives you a lot of AP and health, at the same time as you will slow enemies.

After this, you should really decide for yourself what to build next, as it should be decided by what your opponents are going. But what I usually build is what you see on the top of this page.