When on softer surfaces like sand, grass, and carpet, avoid those zany "super 360 spins". Rather, turn gradually while moving forward. As everyone else already said, just keep an eye on things and you'll quickly learn what your Sherman can and can't do in various surfaces. One thing I've learned, especially with a stock tank, is to avoid worsening a bad situation. If you find that you're stuck in a clump of grass, rather than gun it to push through the obstacle, walk over and inspect the tank to see what is bogging it down. Sometimes it could be something simple, that takes a couple seconds to remove or reposition the tank, rather than risk stripping something then having to spend a while repairing it or waiting for replacement parts in the mail.

It's all about learning the constraints of your specific tank, in its specific configuration, in your specific environment. Increasing your maintenance skill helps offset the increased risks you may take as you become more confident and start pushing the envelope.

And as Fsttanks said, please share pictures of the FUN!