To start with you have to make your angles sharp when you are folding, and hold on tight to maintain that angle. (or use a clip to hold it until you finish tying it.) If you did that and it just needs some sprucing up, try stuffing is with tissue to make it poofy, and spraying it with starch or fabric stiffener.
Also, you may want to check out this post http://hipgirlclips.com/forums/how-m...rfly-fold.html
It has helped me, and apparently a lot of others too.