Good exercises for the SIM include:
Set trim offsets on cyclics. This forces you to rely on your fingers, not the stick center to hover the heli.
Set a large rudder trim offset, then try to fly without touching the rudder. This teaches flying in all orientations, and also allows you to get used to a heli that is pirouetting. I like to set the collective for a good hover, add rudder offset and then try to hover with just the cyclic stick.
Add wind... including gusts. Don't go overboard here, you don't want the wind to exceed the maximum forward speed capability of the model. Gusts are better for reflex practice as they're less predictable.
Change your take-off position routinely. Practice taking off nose-in, side-on and various other orientations.
Set the pilot position further from the landing pad, then try takeoffs and landings at a distance. This prepares you for the inevitable unplanned distance landing.
Increase the "time base" to make everything faster. This improves reflexes. G2 has a time base setting under Miscellaneous setup.
Go to full rates on the collective and rudder, then try to fly. You can also tweak the flybar and paddle settings to get a more twitchy response.
Turn off auto-zoom, then fly out to a far distance. This teaches you to deduce orientation based on how the model reacts to inputs, not based on being able to see the model geometry.
All of these are good practice scenarios. Of course, they don't prepare you for everything but they do help improve your skills, orientation and reflexes.