I'm with scWirral on this one ... as a car driver of 20 years before I did my CBT and DAS, I ended up having to have an extra lesson purely to master slow-speed riding. Now this was mainly due to me falling on me R's (as someone put it) during a DAS lesson :/ It's fine practising in empty car-parks but if you lack confidence then the first thing you tend to do (well I did!) when confronted with 4" kerbs was to grab a fist full of front brake ... hence the bike became unstable and I dropped it
I think all the tips here are great though, and most of them echo what I learnt on that extra lesson:
1. Keep the revs constant.
2. Let the clutch out slowly until you start moving.
3. When you actually START moving, go straight ahead for a few metres first!
4. Then turn the handle-bars.
5. As you do 4. turn your head and look back down the road.
6. Try and keep the revs constant!
7. As you let the clutch out, if you find yourself going faster than you need or are comfortable with, apply a little rear brake (but not too much!) - don't ease off the throttle!
8. Sit up straight and complete the turn
I was lucky that after my test I had to do a U-turn every time I got home after going out on the bike
and can concur that practise helps an awful lot! Have confidence in yourself, and the bike too, and you won't go far wrong
Pete