I have a longarm and am friends with quite a few other longarmers. What I've learned is that we all quilt differently. One friend started out with pantographs and later switched to doing computerized quilting. Another does mostly pantographs and a little free motion. I do only free motion (and ruler work). There's no right or wrong way; we are all happy with the way we quilt. If you are happy doing pantographs, don't feel like you have to do free motion.
On the other hand, if you really want to do free motion, the best advice I have is to practice, practice, practice. Put a practice piece in your machine and just doodle. Angela Walters has some wonderful videos that feature some simple designs, and her books are good. If you don't have a practice quilt sandwich, you can practice on a piece of heavy felt. I learned a lot by taking classes at the big quilt shows. Most of the instructors stressed doodling a design on paper until you have it stored in your memory.
Patchwork is right that you shouldn't be too critical of how your work looks. It always looks better when you take it off the machine and it's viewed in the context of the whole quilt.