1. Practicing the inverted flight be sure to keep a little extra altitude until you know that both you and the plane can recover well.
2. Easy way into stable inverted flight is a half loop. No ailerons needed for entry. Once there use ailerons to maintain wings level and elevator to keep the nose from dropping. If the nose gets too low - recover to upright level flight immediately. (Before the garbage bag is needed)[:@] It may help initially to stop the half loop entry with the nose a few degrees high to give you a moment to adjust.

You (the plane that is) really should be able to fly circles around the field with the Tower Trainer inverted.