Political Parties

I've been wondering lately about what the Democrats and Republican really stand for in their platforms. I consider myself to be generally conservative, but from what I've seen in the news and political discussions, I'm not sure that I'm comfortable with either parties' platforms. I don't think I really know beyond just some vague generalizations. I was thinking about registering to vote for the first time in my life. I took a look at the California voter registration form and was surprised when I got to the part about choosing a party affiliation. Here's the choices for political parties in California:

American Independent Party
Democratic Party
Green Party
Libertarian Party
Natural Law Party
Peace & Freedom Party
Republican Party

There's also unaffiliated / undeclared / independent ("I decline to state a political party") and other (write in your favorite party if its not in the above list). I know a little bit about Libertarians. The others I've never heard of, let alone know anything about them. I guess I'm going to have to make up a list of issues and try to find out where each party stands on them. Could be interesting, but I doubt it. I have the feeling that the other parties are "fringe" parties. I saw some figures showing that the Dems and Reps have memberships in the millions of voters here in California, while the others have less than 100,000 each.