This has been my goal for many years. I haven't run yet so we'll see if it works for me but here's what I'm doing:

• keeping my online presence perfectly clean (I still have all the social media accounts but every time I post something I post as if it will be in the newspapers)

• keep real life clean. I haven't touched drugs and try not to do anything ever that can bite me in the ass (This one is a lot harder and I can't say I'm perfect...)

• network the hell out of it. I go to young professional meetings for think tanks, my party, religious org, etc.

• tailor my professional life to my goals. There isn't a perfect path and if you look at the lives of politicians they're enormously varied, so follow what is right for you first and foremost. I started at a think tank, then worked at a start up, now a corporate. We'll see where I go from there. But I'm trying to make sure I love my job in case this whole politics thing doesn't work out.

• move to an area where you're a viable candidate. Your views should more or less align with the successful politicians coming your state and you should be passionately in love with the place you're representing.

Things I disagree with from below: you don't need to go to law school. That made sense in the 60s and 70s when all the politicians in office now we're young. If you love the law then fine, but law school is so expensive right now it just doesn't make sense for a low paying political career. I'd also say that you can do the low paying work like working campaigns, legislative aid, and research at think tank when you're straight out of college but do yourself a favor and get a real salary after a few years. You always have to act knowing that politics is just as much about luck as anything else and you need to develop a second choice career that can support you.