As GEDA says too much ‘arse over back wheel’ can be very bad but it’s often peoples default position either when things get steep or quite often when they become anxious/scared. I’m going to stick my neck out and estimate that 80% of the people I coach position themselves too far back. The trouble is moving backwards tends to make sense to us. It feels like we’re doing the right thing, your self preservation instincts want you to remove your face/brain from what it perceives to be the danger and it’s an image we say portrayed in magazines, pictures, etc.
Allow the bike to put you into the correct position in relation to it.
Try to ‘plan’ your braking areas in advance. If you don’t believe you can stop or slow down, then you’ll never want to release the brakes or if you do, you’ll just end up grabbing them at the worst possible moment … not a good way to maintain control 😉