How to make a fairy tutu costume?

I was looking on ebay at all these fairy costumes for my daughter and I'm pretty sure I could make one myself for cheaper. She fits in a size 12-18 probably.. I was just wondering if anyone had an specific information or links to help me with this.. I've seen videos and instructions on how to make tutu's but i want to make sure I do this completely correct and was wanting instructions to help me out.