when i first starting wearing hair,,, that was the problem for me too.. the back was like a pain in the ass, but as you progress, ull get it. listen to what people are saying and don't be scared .. cut a little and check it, cut it a little check it. the more u do it the more ur confidence will grow and you will get to the point where the back is no longer a big issue. Slightly less density helps and using thinning sheers and / or razor combs.