In reply to Vampire:
How you drive up from a dropknee depends on which direction you're travelling in. If you're going in the direction of the dropped knee, you are pushing more off the front leg that's not dropped, so your big toe inside edge. For the dropped knee foot you are twisting in on the outside edge with your little toe, and sort of pulling in a bit to keep the foot on.
Going straight up, it feels like bridging, with the push from your big toe on one foot opposing the push from your little toe on the foot with the dropped knee.
Going in the direction of the non-dropped leg is the hardest and can sometimes be hard to push off. You are basically standing up off your little toe on the dropped leg and have to push hard and pull in with the foot at the same time.
Make sure you're practising on an overhanging wall as there is little benefit to doing drop knees on vertical or slabby ground. Generally focus on your hips twisting in and up. Vary which foot you place first, but always make sure you focus on giving yourself room to pivot off the foot on the dropknee side, as you will be rolling from inside edge or frontpointing to the outside edge and little toe.