Emily gives good advice. That's about it. Make sure you have a smooth surface on which to skate, don't do too many downhills on your first day and you're set. Did you roller skate as a kid? I sort of never stopped.
I roller skate sometimes for fun. I have white skates with hot pink wheels!! They're still a roller rink around here. Some of my friends do roller derby, but I'm too scared. If you're into getting bashed around (and having fun!) you should look for a local league. Roller derby got brought back in a gigantic way about 5 or 6 years ago, and it's still going strong. I'm sure there's one nearby.