So first things first. The machine. Hopefully you already have one or access to one. We'll go over models later.
It is so important to practice your stitching. I recommend printing out a few copies of the pages here:
Practice pages [linked from kids-sewing-projects.com]
and then sewing over them, without thread in your needle. Use an old needle as well so you don't dull your nice ones. This will help you turn corners, round edges, and get you used to the speeds you should work with. Practice your straight stitches and fiddle with the stitch length, and try a zig zag, try a few of the more decorative stitches as well. This will give you a good feel for several stitches on your machine.
Practicing this will help as we move into more fun projects and those beginners out there will feel much more comfortable with their skill level.