Personally I find front fulls easier mentally, but for learning technique back fulls were a lot simpler. In a front full you land blindly, which messes with your perception and you have to really make sure you're getting enough height to even got over cleanly. (Nobody likes a twisting ball of death.) Where in back fulls like tucks and layouts it's all mental; if you have good technique and aren't afraid to go backwards you should be fine. :) That being said, having a clean layout and then slowly adding turn progressions should be used before whipping the skill out on the floor. The foam pit is your best friend! ;)