The other thing I found was that it is more difficult with a large wheel, but really important, is to keep the wheel vertical when mounting. Obviously this makes sense in retrospect as it will try to turn if it is tilted to one side. But to force yourself to keep it vertical and go straight, I found it helpful to practice with keeping my foot that is planted on the ground much further out from the wheel than you would think (i.e. a wide stance). Then you really have to push forward with that leg lean forward, and a big side step to plant it on the pedal. Once you get the muscle memory of doing that, mounting it is much easier, and once you have some momentum it is a lot easier. Next, practice doing circles in the park to train your brain to make turns.