Lots of good suggestions have already been posted. Why not stick with pre-cuts if you're having trouble cutting. There are some great layer cake and jelly roll patterns on the Moda website. Keep it simple and take one step at a time. Once you feel confident with the sewing, move on to cutting. Remember - your worst critic is you. If it's not perfect don't sweat it. I've got some examples of really bad cutting and sewing in my collection but I'm proud of every one of them. I learned something with each.
My number one suggestion: Don't be so hard on yourself.