Call however many fouls you need to call to keep the game under control, and make it a good game. There is NO set number of fouls that a reff must call or not call. If a commisioner was watching, he would not not give you games on the reasoning "he called too many fouls that game.", unless the fouls were bogus and bad calls. If it is a foul, call it. You will get yourself in trouble by looking up at the scoreboard or in the books and trying to "even it out", or trying to not go about 40, and basing your officiating on how many fouls others call. It is your game, you're the boss out there, call what you see, have fun, and get paid for it!
Good luck,
Doug