I got some suggestions, but im not sure if this work for everybody so here is:
1- Play STEP MANIA or Dance Dance Revolution in PC (for example) to be better with your right hand (the hand which push the buttons) as fast as you can play or win in this game in the hard songs you can see after you play that you can take more control of your right hand then practice combos of: Sheeva (Complete Chain, Hp, Hp, LP,Hk, Hk, Lk, B+Hk), Lui Kang: Hp, Hp, Bl, Lk, Lk, Hk, Lk. Kung Lao: Hp, Lp, Hp, Lp, Lk, Lk, Hk. the hard one: Jax: Hk, Hk, D+Hp, Hp, Lp, B+Hp.
2- For the Left Hand use this configuration in the STEPMANIA:
Left Handed: W=UP Arrow - S= Down Arrow - A= Left Arrow D= Right Arrow
Right Handed: in the alphanumeric board: 8= Up Arrow - 2= Down Arrow - 4= Left Arrow - 6= Right Arrow.
This will help you to sincronize with your hands
When you can complete this make sure to choose your main char (don´t care if is a hard char or not, the thing if you feel confortable with that char).
Then play against CPU. Beat the game with some chars
now you´re ready to match, to know more about how to match there are some match videos on you tube, the match videos section.
there are some names you can write in Youtube to watch some matchs like: RZP, Hanzo_Hasashi, Ded_, Shock, Lexhibition, Konqrr and some more.
I hope this help you to be ready in UMK3