Just a little tip from me. I love to sew with denim more than anything. It doesn't always have that "oh so adorable" affect, but it works. Whenever I want to try something new, I just tear up an old pair of jeans and get to work. It's sturdy, completely machine washable, and it's free! It also makes life a little bit easier for all of your pressing (ironing) needs. So, next time you want to go for a test run first on something, just try an old pair of jeans. You'll have your results in no time!
Also, I've discovered that a lot of people also use just their old clothes to make things. For example, I have this favorite black-flowered shirt that I just love, but it just doesn't fit anymore. By using it with a project I'm still able to keep the fabric that I love by just cutting it up and sewing something fun, like a diaper bag.