Tough invite to get. I know a kid who made the underclass team, but never got invited to the tryouts his Sr year. If your in Chicagoland/Southeast WI your best bet is to align yourself with a team in the Chicago Scouts Association League. Justin Stones Elite, Sparks, Hitters, Longshots, 29ers, Athletic Barn, Pro-Player, etc. They seem to have the contacts, but even then it can be tough. I know many of them are conscience of their reputation and wont work those contacts for all their players.
As Gov said, I think the Hitters are the hot program right now. I would try to get on their team, or at least get in front of them. Other then that Sparks, followed by Elite and then Longshots seem to have the most pull.