I've tried to talk on my blog about starting in comps, from the viewpoint of a newbie instead of an expert giving advice down to the neophytes. I've only done 5 comps, and the first one we went to completely cold.
I hadn't done a whole lot of reading yet, though I'd done some. I just wasn't on a site that had a lot of people that competed. We went to our first comp before ever visiting or anything. We now try to hold a spot for someone new that wants to tag along to see if they like comps or not without having to jump in. That said, I'm glad we just jumped in. Though other teams have done better in their first 5 comps, a lot of that is due to a lot more prep before their first comp. We went to the first one to learn, and tried to soak up everything we could. We still do that, and we're starting to have some small success. We at least now have a slight clue as to what we're doing, where we didn't really the first time, though we didn't embarrass ourselves, either.
There are several routes you can take to competing. If you're nervous about it, find a team to apprentice with. You can also judge first, to get an idea of what's being turned in, and talk to the teams the night before. Most teams are more than happy to show off a bit and give you some ideas. Some have their secrets, others don't keep anything secret. All have been willing to talk, though... Just not during turn in time! I for one become a bit of a jerk during that time, and I can admit that... luckily my team and my wife love me and tolerate it!