Always wear a parachute when flying aerobatics, or aeroflot, you never know if the previous pilot went over the limits.
DO NOT tailslide a 150 and make sure to check the elevator attach-bolts.
happy flying, being upside down is great, you should try a mudry cap 10 or similar, having the instructor next to you instead of behind you makes it easier at first for him/her to explain and you to understand.