I've shot a lot at Rockcastle, but won't be there for the GSSF match. I worked as a range officer a couple of years ago at the first GSSF match they had.
A couple of helpful tips-
1. When you're waiting for your turn to shoot, help paste targets. Not every shooter, but at least several. Coming from a USPSA background, it really blew my mind how so many of the shooters at the GSSF match just sat around doing nothing until their turn to shoot. The ROs will greatly appreciate it and it will give you something to do.
2. With GSSF scoring, it's all about accuracy. Shoot only as fast as you can and still keep them in the -0 ring. Penalties are huge.
3. Don't talk to the guy carrying 2 aluminum gun cases/brief cases. He's far too serious about this shit to strike up a conversation with someone. (no, I'm not kidding.)
4. Most importantly- Have fun and be safe!
There will be a steel challenge match on June 18 at Rockcastle, in my experience, the crowd that attends Steel Challenge and USPSA is a little more lively (and friendly) than GSSF.