Don't try to to do much to start with! There is a big learning curve when you are stitching on a longarm. You can't run if you don't know how to walk.
Start with simple meadering. Once you get that stitching out the way you want, then and only then move onto a new motif. Practice on paper or a white board helps with the learning curve. Don't try say - leaves - then think, "I can't do those." Then try something else and think the same thing. Get one down pat first - then move onto a new design.
I hope this is making sense to you. Get some cheap muslin and practice on that. Don't jump in and put a quilt on unitl you feel comfortable with it.
Like I said before - there IS a learning curve here. You have to find how high off the bed of the machine the quilt needs to be and many other things. Take it one step at a time and RELAX!
If you take it slow and realize you can't put a quilt on the frame and quilt it and have it look the people who have been longarming for years. It will come, it just takes time - and PRACTICE - PRACTICE - PRACTICE !!!
I have read on another forum that it takes about 300 hours to get really good.
You might want to think about joining the yahoo group - homequiltingsystems. I have learned so much from this group. I don't know what I would have done without it.
Good luck and remember - the frame is your friend!