As many others have said, it's mostly just putting yourself out there. I started RPing roughly over a month ago, because one day instead of just running past all the people /saying in the Quicksand, I stopped to talk to them instead. I had lots of missteps and bad decisions the first few weeks, and probably alienated some people, but overall I made lots of new friends, and became involved with lot's of stories. So yeah just put yourself out there, it is of course possible that you might screw up at first (like I did) but eventually you'll find you niche and discover how you want to play your character.
