If I can do it, you can do it.
2005: Went with one friend. Was quiet, and met up with a few of HIS friends. I felt out of place.
2006: Brought young brother with us. Friend's girlfriend at the time came with us as well. Wasn't too comfortable with my brother that year with us. Made the year kind of a living hell for me, but I also was inspired in 2005 to make AMVs, so this was my first year competing. Was worth it to be part of something, without being infront of people.
2007: My two AMVs made it into the contest. Didn't win, but felt like I was part of it. Friend of my friend's girlfriend joins us this year. Pretty enjoyable year.
2008: First real cosplay. Sadly, my hat didn't work out for me. Pants were too tight, but easily replaceable. Felt like a mess still.
2009: My first year MtF crossplaying. This took a bigger jump in guts than anything before it. Walking out in a dress and heels was pretty darn scary outside of the hotel, and my makeup suuuuuuuuuuuuuuuuucked. I mean, I was orange. Seriously. It was awful. I try to forget that year, but I am sure others won't forget the orange male Chii.
2010: Returned to try as Chii and tried better. Still kinda failled, but wasn't orange, so yay!... Eyes bearing down on me still kind of uncomfortable, but I didn't let that get to me.
2011: Crossplay becomes near-second nature. Get a Cardcaptor Sakura crossplay. Greatly improve. Friends see me, and one was shocked at how much better I have gotten. Less eyes glaring.
2012: I trapped a gameshow host. Made my year. Sure, I was in front of an audience, but you know, when I was in that moment, it was awesome. My team loved me. The host called me "Secret surprise" If being infront of a gameshow in a dress didn't build me up, nothing would. In the end, we won, I knew alot, and my team actually looked at me for a bunch of answers.
So, from 2005, I am there, just me and one friend, and me being super quiet, to 2012 with me being a decent cosplayer/crossplayer who has the guts to get up on a gameshow stage in front of a huge audience.
As you can see, I segwayed myself to where I am socially these days. I try for fun. I say, go with a friend, and start from there. Being accompanied by a friend should help loosen you up. Once you are into the con, it will feel like home, and everyone not at the con will practically be ignored.