Aside from the spinach which probably the best advice haha you can try doing L-muscle ups.
If you have a set of adjustable rings, place yours feet on like a spotting block so that you can hang in a false grip of the rings with your legs on the box. So you are like in a L-hang. From there you can work the muscle up and used your legs to help yourself a little bit if need be. This can be sometimes a good intermediate step between muscles by yourself and with some help.
Otherwise yeah pretty much what was said before. Work on doing fast explosive chin-ups, dips, and work the transintion phase with a spot.