Dont try to bat in the "highlights"
Bat for time, the runs will come, (unless in the final balls of the game and you need runs quickly) . Play each ball on its merits, that is, block or leave a good ball and hit the bad ones.

Play to the conditions
 If the pitch or weather conditions make it hard to hit the ball, defend more, it can be a bit boring, but it will help your score runs. Leave the bigs shots til later.

Find out what type of cricket player you want to be
 Find out what you like or figure out what you want to be and stick to that. Not everyone can be everything. If you cannot see the ball then probably you will not be a batsman.... i e Chris Martin. Find out your ability and stick to that.

Hand to eye coordination
Use a golf ball and narrow stick: Throw the ball against a concrete wall and concrete pad or path below it, this will improve your hand-to-eye skills. Play test matches in your mind while doing this.

Using a ball on a string,
 (in a sock or stocking) to practice your defence is a great way to get repetition. Doing this for long periods of time can help your concentration too. Concentration is vital for a batsman to stay in for any length of time.

Practice as though you are in a game situation, dont muck around!
When practicing, invisage yourself in a game sitiuation and what you should be doing. This will help you on gameday. Net batters who look good, dont necessarily do well out in the middle, where you can get out!