Theres been numerous threads on this, and I'm guilty of starting one myself. A few people will probably answer anyways, so no worries. Here's the thread I basically asked the same question and got the answers your looking for.
http://www.subsim.com/radioroom/show...leave+me+alone.
But basically, deep (I like to go to 150-200m), slow (50-75 Rpms, click just below 1 knot on the speed setting), and long slow curves (10-15 degrees rudder).