I honestly don't know the best way to shift an automatic. I usually out it in drive an let the auto do it's job and when I need some extra speed I shove the trottle to the floor to push it into a down shift.
However I do assume it is similar to a manual. Listen to the engine. Ignore the tach after you get use to the way the engine sounds and then after that listen to the engine. The engine will always tell you when it wants to shift up.