How do I not stall a motorcycle?

I started taking a beginning riders ed class on Saturday. We're using little 250cc bikes to learn, but I kept stalling mine when I would try to take off. I would add a little throttle, then slowly release the clutch, but the bike would always lurch and stall. Any pointers on how to calmly and effectively get going without having that issue? No problems when I actually got going, just when I started.