Draven is currently the strongest early game ADC. He will burst someone down quickly. He is best with an aggressive support for the fact that he needs to get fed as fast as possible. Once he is fed, he can easily destroy anyone in the game with great positioning.

x3 For if you can dominate your lane.
x2 For rushing Bloodthirster(Most efficient).
If you have a sustain support.

Blood Thirster Always aim for this at first for the damage and sustain.
Right after Bloodthirster.
You are not an ADC without this item.
Only get this item if the enemy team has 2+ people with quite a lot of armor. DO NOT get this item first.
Build this if the enemy team has a good amount of cc and AP.
OR Your choice on whether you need more health or more damage.
This item can be built after Infinity EWdge if you feel you are dying too quickly or they have a lot of gap closer's.

PROS

High damage, Good Mobility

CONS

Squishy, Destroyed by CC

Best not to go Draven against a at level 6.

Use your to cs. Try not to push your lane too hard and make sure you harass to starve their ADC. Push your lane if you wish to kill the tower. However, it leaves you open to getting ganked. Make sure you know where the enemy mid and jungle are. Also make sure that the enemy team doesn't have global ults. If they don't have global ults, feel free to push. If they do, then be very careful. 's save lives. That is why you have a support. c: