One thing I've discovered about origami is that I tend to make a lot of mistakes when I'm learning how to fold a new model. In the beginning, I used to try to fold and unfold the same piece of paper instead of starting with a fresh sheet. I'd attempt to make a slight adjustment, then get frustrated when I couldn't remember which fold was the "good" fold and which fold was the "bad" fold. Then, to make matters worse, all of those extra folds threw off the alignment of the project and made it even more difficult to see if I was following the directions correctly.
If you're new to origami, the best advice I can give you is to remember that paper is cheap! Give yourself permission to make mistakes without worrying about wasting paper.
Use colored typing paper, wrapping paper, or square memo pad sheets for practicing. When you're ready to move on to actual origami paper, use your least favorite design in the pack first so there's less pressure to get the model completely perfect.
If you're really thrifty, you can always use your mistakes for a decoupage project or shred them to make colorful packing material for use in wrapping gifts.
Using them to make handmade paper could be fun as well. The process of making your own paper is time consuming, but these sheets make lovely covers for folded origami booklets.