Re: Need shooting help!
Rather than a "shooting school" consider getting involved in F-class prone competition with that new .308 rifle. Most of the NRA highpower F-class guys are very friendly and helpful with new competitors. With F-class, there's not a lot of specialized equipment required either. Put the rifle on a bipod, get a rear bag for it, and go shoot.
A typical F-class/prone match is 66 rounds for record, broken into three strings of 20, plus two "sighters" for each. It will teach you to read the wind and mirage very well. Matches are held in pretty much every state, nearly year-round. We even shoot here in Washington in the snow! Silly us. Shooting with the other match shooters is a wonderful education in precision shooting at long range. F-class is out to 1000 yards, so that should scratch your long-range itch!
If you're hooked on a school, I believe there's a place down in Texas called "Rifles Only" or something like that. Has a good reputation among the sniper-types.