One word. Relax.
I guarantee you will be dropping catches or fumbling the ball because when it is flying towards you, you are worrying about dropping catches or fumbling the ball. You tense up, go hard at the ball and thats when problems happen.
It is a cliche, but let the ball come to you. Don't move yourself to where the ball is, move yourself to where the ball will be. Think of taking a catch, whether it be simple or difficult as not stopping the ball, but bringing it to a gradual halt.
To start with, go out into the garden and lob the ball in the air and just focus on getting into position. Once you sort that out the rest is easy. Don't be scared of the ball or you will never sort it. Be condfident.
Practice practice and more practice. Practice in the garden after work, practice in the park when you're not playing, practice at a match when you're waiting to bat. Even practice when sat watching telly, just lob the ball from one hand to the other. Sounds daft, but it really does help. Learn to know how a ball reacts when it hits certain parts of your hand and learn to counter that by making sure you get your hands in the right place.