Advancing the throttle slowly on takeoff is ok, but regardless of how you advance the throttle, the more important thing is to not rotate until it has good speed. Just keep it on the ground for an extra second or two - You may be familiar with the term "Horse it off the ground" - That's exactly what you DON'T want to do.

Shallow approaches are not necessary, just don't let it get too slow in the final turn.

Here's the deal - Look at the Decathlon (Or Citabria). It has the same basic looks as a Cub or Cessna, but the big difference is that it has a very short tail moment. That is, the tail is close to the wing. This allows it to be much more maneuverable, but it also greatly reduces the tail's effectiveness at low speed.

So it will float in very nicely. BUT - If you're floating in very nicely, and then zip up the throttle, you don't have enough tail back there to prevent the torque from spinning you into the ground.