I use stan james because they are one of the few bookies who allow a treble like the one I backed. A lot of other bookies i've tried say it's related contingency. I have stats on referees points index from the last few seasons and all the corners stats from last years premiership sides.
As for the total goals, I just take it as it comes and see how the team(s) are performing at the time.
Last nights corner count was incredibly high at 20. The average is around the 10 or 11 mark. The prices and spreads for bookings points change depending on the referee or teams. Usually the 'upper' band is about 46+ pts, but for last months Old Firm game for example it was 56+ pts. It's 10 pts for a yellow and 25pts for a red.