You will fall. A lot. When I started, it took me about 5 days to get it. Granted, I was really young, I didn't listen to instructions, and I only had 1 lesson.
You'll pick it up over time, but I'd say the biggest thing is probably to be confident and stick with it. If you're afraid to go fast, your progression will be much slower since you won't be able to get comfortable with changing edges. I used to wait until all the people on the mountain within view had passed me before I stood up because I was worried that I would cut someone off, but you've just gotta ignore everyone and focus on what you're doing. They'll get out of the way as long as you're kinda off to the side. Also, don't get discouraged. For me at least, I went from absolutely sucking for 5 days to actually being decent in the period of like an hour. Once you get it, it will just click. Then it's just a matter of getting more comfortable on the board.
Anyways, just stick with it and you'll pick it up! It's definitely worth it once you get it down.