Whatever you do, if you are fielding, don't let your captain place you at silly-mid-off. It's just asking for trouble.
Rather than trying to whack the ball over the boundry when you're batting, try and kill its momentum by deflecting it into the ground, it's not a very exciting play, but it's a safe way to get rid of that annoying fast bowler as they only get to bowl until the over is done.
Technique:
stand sideways facing the bowler (right handed) plant your right foot and step forwards towards the bowler with your left keeping the end of the bat slanted towards your right instep. If you do it right you will kill the ball's momentum (like hitting a corner when playing squash) by deflecting it onto the crease infront of you. Plus you will be covering the wikit with your body, so all you have to look out for is getting out 'leg before wikit'. If the fielders can't catch the ball then the bowler has to move on when the over is finnished.
Hope that makes some sense
EDIT
here's a pic of what I mean:
