Negatives, jumping (minimal just so you can make it up using mostly your strength, make the bar higher as you progress if possible), and assisted if possible. You need to build a full ROM dip as well, the transfer from pull-up to dip will be worked after both a powerful pull-up and full rom dip are formed. For dips if you can't do them, do jumping, if you can do them decently, work the rom until you can go no lower. Bench dips are also effective in learning a dip decently well, go from feet on floor then elevate, once elevated is easy, you should be able to get a dip on the p-bars, not a full rom of course, but a start. Pull-ups need to be worked as a full rom as well, need to be able to pull right up to your lower chest. So work on those things and you'll have a good pull-up in no time. Muscle-ups take work though, it won't come easy, work at it and don't give up!