Everyone has given you great advice. So much is practice, practice, practice. Definitely take a maintenance class as you'll need it at some point. Lots of good books and YouTube out there and take any class you can. I've been fortunate over the years to take from Sally Terry, Pat Barry, Jamie Wallen, Dusty Farrell, Angela Walters and Kris Viera--learned something every time. Also, if there is a long arm or machine quilters guild in your area--join! The one I belong to only meets quarterly but each meeting has a great program and I've learned so much in them it's well worth the membership and time--plus it connects me with other long arm quilters who I can ask for advice.

Make sure you get the height of the frame adjusted correctly. Otherwise you live with a lot of shoulder and back pain. Oh and you might consider doing yoga after each session.
Seriously. Haha!
It gets easier and as you RELAX, less stressful

Practice, Practice, Practice. I also took a class from Jamie Wallen and drawing helps. I free motion most of the time. I call it doodling. Start out by doing e's and L's, then do circles, squares, stars, anything doodling. Like others have said don't be afraid.

Nothing beats lots of practice. How to get a lot as quickly as possible: contact local quilt guilds and groups and donate your quilting for their charity projects. These are utility quilts and whatever you do will be appreciated. This way you get the practice and the charity quilt is finished.

I became a YouTube junkie when I bought my machine. The one that got me started on the right track was How to Use a Longarm quilting Machine by Sparrow Studioz. It is a wonderful video. After that I searched YouTube and watched videos on Pantographs and rulers. Handi quilter has a wonderful library of very helpful videos that are all free on You Tube. I don't own a Handi quilter but still learned so much, especially about ruler work, watching their video and, of course, then purchasing their rulers! If you want to do ruler work http://www.terylloy.com/Quilting-Videos.html has some good advice,too. I have had my machine about nine months and love it!