wait hold on, an uppercut punch or kick. for a punch, you try to go down, start low, and then use a lot of your legs to go high and swing up for a punch
Um no, there is no such thing as an 'uppercut kick'.
Tips: Merely try to get into a low position, where you could rise in force, and aim directly into any bodypart you chose. Make it look as natural as you can, expiriment, you'll get it.
But anyways, try to do a low punch, bunch when extending the elbow, raise your arm up and contract/extend pecs/twist torso for more power and making it look more realistic depending on what hand your punching him with.
I am not sure if your allowed to post how to do moves but try to start of lowering your arm then raise using the pec to contrast or extend to position it to the player, here is one way to do it try moving some of the joints to break a part of uke.