I have a diesel and I was told the best way to start it was:
1. Press clutch
2. Turn key one notch to start electrics.
3. Wait a second until the glow plugs light on the dash goes out - this gives them a chance to warm up before actually startng the car.
4. Once light has gone out, turn key to the next notch to start the engine.
5. Release clutch, or engage gear and drive.
Not sure if the glow plugs thing is correct or not, but that's the way i tend to start as it only takes a second or so for the light to go out before I can start the engine.