I am still getting to know my system too - well, actually, I'm upgrading my 'mid-arm' to a 'long-arm' - should be in shortly.
I went with the Pfaff GrandQuilter (has a 9" harp), have been terribly frustrated with the limited room - could do lines but couldn't do the nice designs in blocks. So my 18" is due to arrive next week.
I've tried all kinds of things just to get the quilt on the frame - pins, secondary leaders, channel systems, velcro. Right now I'm pretty happy with velcro on secondary leaders.
My most recent discovery was to pick up some heavy vinyl (the kind you might put on as a table protector), cut the width of the area I can quilt - so I have an 18" x 36" rectangle (bordered by blue painter's tape). With that on top of my quilt, I can practice and audition a quilting design. Pretty cool - get the muscle memory going, see if you like it on your quilt. Mark with washable crayola markers - just wipe it to start fresh.
I also bought some mirrored tiles, have those on the bed of my frame, so I can easily see what the stitches look like on the back - shine a flashlight on the back, see the stitches in the mirrors.
I've also been watching lots of videos - search you tube - there are lots available to pick up tips and techniques.
I also did up a sampler / practice pieces - picked up a bolt of muslin from JoAnn's, play with designs and tools. Another tip I picked up somewhere - likely Sharon Schambler - is to pin a narrow practice piece right along side the quilt you're working on - that way you can warm up without having to take your quilt off, and also to check that your tension is good after bobbin changes.
Hope this is helpful!! :)