Learning how to drift on a motorcycle...?

Originally I would have said it was a skill learned on the flat track/Speedway circuits.

Now I think its more down to Supermotard racing

I would Suggest trying a Supermoto Bike. (Great Fun)

something with an extended swing arm will give you more time to deal with the spinning rear wheel, easier to control the direction.

A small piece of advice though, When a sliding spinning wheel GRIPS - its then called a High Side.

High Sides Hurt, A Lot !

Edit..

Oh I forgot to say, it might be harder to learn on soft ground, how do you get the grip back if your sliding on moving ground, rolling off the throttle wont help.

I would try a Supermoto on tarmac with slick tyres, you dont need to be going fast.

@Matthew - Its definitely called drifting in the same sense as Ken Brock would drift in the Gymkhana

http://www.youtube.com/watch?v=20XsaHpRQC8

http://www.youtube.com/watch?v=VYpOFimB7ZA

How To Drift A Motorcycle

It isn't called drifting, it's called rear wheel steering. Best learn off road to start before trying to transpose the skill to the track.

Drifting as in stunt style rolling burn outs ? or rear wheel steering ?

If you mean sliding the rear tyre out of corners, then dont waste your time. Yes it can be done, but there is a reason why you only see the fastest WSB & MotoGP riders doing it.

On gravel no dude you'll die