If you already have a decent flight sim, then loading in an aircraft as close as possible to what you will be flying (in most cases, you'll be able to get an identical one right down to the panel)
Will let you figure out where everything is, you can do proper "Hanger" flying and get familiar with your surroundings.
You can play with manifold pressure, throttle, prop settings and see what they do in an environment where you are not going to break anything.
Sims are great places to practise everything.