If you don't have experience riding in a pack, I would try to find some good group training rides before doing a crit. Being able to ride fast in large groups is key to not crashing. Also, make sure you are comfortable cornering.http://www.chicagobikeracing.com/index.php/rides
-- this site lists a lot of group rides, as well as probably the most comprehensive list of road races in the Chicago area. if you're near Evanston, the "Judson" ride is a good taste of what a road race is like.
As previous reply said - crits are fast and furious. Did a lot of these when I was younger. don't miss them.