Great tips by Evadman. Read all the links, and grab the best tips from each. Take your time and do it right from the start. It will be slow at first, but worth learning. Don't try to get it done in one coat. Don't play with the wet mud too much. Try to scrape it, so that you won't have to sand at all. It might take longer to be that meticulous, BUT IT'S WORTH IT! Again, don't play with it a long time, but scrape it down flat on each coat. Use a nice topping compound for the last coat. Good stuff won't leave bubbles, and will spread easily. Don't be afraid to add a little water to the mix, it helps a lot. If you don't have an inside corner trowel, finish one side at a time. You can buy faster setting compound, if you want to do more than a couple coats in a day.
It's worth repeating, that you can apply it, so that it requires very little sanding. Strive for that!