Keep reading. Read the papers. Read TIME magazine, and read some of the more credible websites that have some kind of slant (aka The Nation, DemocracyNow.com, The Weekly Standard, etc.)
If you feel strongly about politics, and about certain issues, I would say that its generally motivated by things you have seen in your own life. Your political beliefs tends to be a reflection of the way you look at life personally. It all ties in together in the end.
My personal experiences were coming up in a New Jersey working class home with a Democratic mother and a Republican father. In my family, politics and religion were always around, always being questioned, no matter who said what.
The jobs I have worked and the things I've seen also have influenced the way I look at things.
I would say that if you read the politics forums, read the papers, and are aware of what's going on around you, you already are more informed than the rest of this country...being as most people don't pay attention at all (sadly).