Welcome to CW - we've had plenty of threads like this about coaching tips before, and we're looking to introduce a dedicated coaching tips section soon as well.
Reuben (Lord) has made some cracking tips above (as you'd expect, he can't do much but he can bowl offies), just thought I'd add a bit (Waughney and Aust_Hitman can vouch for the effectiveness of my coaching tips).
Big danger here is that we go on and on with tips and that over-complicates everything and confuses the hell out of you. So, I'll try to keep it short and simple, but feel free to ignore. The grip wants to be wide, but not too wide or you'll slow down the ball release (friction).
Try keeping your right arm (I assume you're right-handed) as high and straight as possible, this will both increase the bounce and turn you get (if your arm's not straight any revs you put on the ball won't give their maximum spin), and very important get a good, strong pivot round your left leg, so that your front shoulder points toward the batsman after you release. If you don't do this, you end up just putting the ball there, which just asks to get carted.
Finally, look to vary the flight and pace of the ball. Slow bowling isn't just about beating the batsman off the pitch with turn - it can be equally satisfying to out-think somebody by inducing them to play completely the wrong shot (bowling someone with a googly's great).
My MSN is in my signature.
i bowl left arm orthodox (i thought the name might have implied that...despite the typo)
