Level advantage Vladimir

Honestly, the best way to get a level advantage is to bully the enemy out of lane forcing them back and then sustaining yourself in lane as long as possible.

With Vladimir this is/isn't hard at the same time. Vladimir is one of the best sustain champions but he needs a few levels in order to be a sustaining bully. The first few levels most champions can actually bully a Vladimir out of lane simply because he has no damage to trade with and his sustain doesn't do much yet.

I suggest early levels trying to let the wave push towards your turret. This let's you play the safest so that the enemy has less room to try to force fights upon you. Once you get level 5 or so you can finally begin trading a little bit because your CD from Q has gone down. By level 7 you should be great at it. At these times you need to try auto + Q harassing as much as possible. By this harass you can force them to go back and then shove the wave as quickly as possible into their turret making several minion waves die to it. Don't forget to go back yourself though because you don't want them to come back with big items, force you out of lane, and then do the exact same thing.

Also, if you manage to shove your lane fast enough you can potentially run to nearby jungle camps and take them for extra exp/gold.

EDIT:

This is really the only reliable way to ensure you are ahead in levels. You can never expect kills or jungle ganks to get ahead. It's a really dick move to steal exp from your jungler at their buff because it delays their level 2 which hurts them really badly. Hurting your jungler that much gives you a slight boost to level 2 in your lane but literally puts your entire team behind because your jungler won't be able to gank which will likely lead to a rage fest between you, your team, and your jungler.