My guy allows a straight 10 on the 3 gamer. You get the 1/2. I've lost 1 3 gamer and bet the 3 game every week of the season. I've been doing it for xtra cash since college.
Basically, I look for good home teams with big point spreads, tease them down as close as I can to pick em. If I have to take a roadie I will, but I prefer home teams. I stay away from "Game of the Week" hype and always go for any game that I perceive could be a blowout. I also try and avoid division games if possible, too much familiarity there.
I tend to stay away from teasing the O/U, but will on occasion if I can't find a 3rd game I like and there is a great defensive matchup. In that case I'll usually tease the O/U down and take the O.