When approaching the wall, first put all your weight onto the back tire until you touch the wall. When you touch the wall, send all your weight over the front tire, dont be scared of lifting your back wheel, nothing is going to happen. When you are about to drop your back wheel try to feel where your balance is and try to place your back wheel in the best possible position to not loose your balance.

Lean on the wall harder and pull back more

Lean on the wall harder

throw yourself back after you press against the wall

lean back and look at your stem of a part of your bike