I just got my LA this summer and I am only on my second quilt. I also draw out designs a lot! Got myself a big pad of paper and just go to town. I doodle at any given opportunity. I am getting really good at drawing free hand feathers so I will try those on my next quilt. On my very first quilt I drew out the block and then drew my quilting designs on the block. I practiced on a one yard sample sandwich made with super el cheapo fabric and a piece of W&N. I knew I wanted to do pebbling so I practiced that a lot. I would be nervous learning LA for the first time on a real quilt. I think a sandwich of fabric you don't care about is better. I do not want to fall into the trap of doing nothing but meander so I really push myself to do anything but, in fact I have yet to do meander on my LA, even on the practice piece I did anything but. Here is a link to pics of my very first quilt off my LA that I just completed a few weeks ago.
http://www.quiltingboard.com/t-77776-1.htm
It was a combination of using a stencil (you can still see the chalk in pics) and all freehand with no marking. I have not yet done pantos. I did take a class at a not so local QS on an HQ16. In that class they taught us how to load the quilt, follow a design using the laser light and using the groovy boards. Then they let us play doing freehand whatever we wanted. I ended up buying an Innova which just felt much nicer to me when I tried it. You will be fine. Just relax and have fun. I absolutely love LAing.