While I'm no expert, I do quilt smaller projects--although they seem to be growing--did a twin size spread for my DGS last Fall. I totally agree that the Leah Day videos/website is a must. I have it marked as a favorite on my computer so I can pull it up for each quilt. Also, from a class I took for Long arm quilting, I use a white board and dry erase marker to "practice" my design before I thread the machine.
I've found that using a higher # thread (a 40 or 50 wt instead of the 30 I usually piece with) and a larger needle (a 14 or 16) seems to stop the skipped stitch and thread shredding that sometimes happens.
Getting the hang of the speed is what is hardest and most important--remember that your machine should be working a bite faster than you are so that curves don't get "eyelashes", etc. And if you are tense or tired, it seems your speed gets more erratic, so take a break every once in awhile (some people recommend some wine before quilting--doesn't help me!).
The 2nd hardest thing is moving a fairly large project through the machine--having tables surrounding your machine to hold the quilt level helps some on this, but sometimes you just have to roll or squeeze the quilt in the harp space in the machine and work slowly to keep it moving without pull.
And like everyone else is saying--practice, practice, practice--even then you'll get somethings that just aren't quilt show quality--the idea about placemates or table toppers is excellent. Good luck--I've found that I like the quilting process too, and have decided to get a long arm in 2013!