The "rules" (a.k.a "tips") are always the same
1. Have enough altitude when you try something new.
2. Follow the maneuver through. If you are trying to do a roll or loop, enter the maneuver with the heli pretty much level, and do not interfere until it has completed what it is doing (do NOT try to correct for intermediate positions unnecessarily).
3. For roll and loop, negative pitch while inverted is highly recommended, but you may be able to get away without those initially (assuming you have enough altitude and you drive the maneuver with cyclic much more than collective/pitch).
4. For inverted hovering, practice "punching out" (gain altitude while inverted) on the sim, and be aware that the amount of negative pitch you need to arrest the heli from falling may be very very different than the sim. Again, altitude is a friend. Also, do it at a bit of distance in front of you, so that the heli does not end up directly above you at any time during the maneuver.