the mental side of the game is the biggest thing you should work on, you can increase your average by a big big margin .....
You need to employ a mental techniques to a few areas ...
Before the game you must focus on the match, run through what you want to do, run through the bowlers you will face and what you are going to do to score 100.
during the game you need to focus your mental techniques on:
1. your composure .... dont get too wound up, too over confident or in too much of a lull.
2. your concetration ... you need to foucs your concetration as the bowler is running up
3. the opposition .... never ever shy away from a confrontation with the fielders/bowlers, if you have points 1 and 2 perfected it wont affect your game. Dont be scared to tell a bowler what you think of him and meet him half way down so he could get a better look at you.