In my opinion, it's imperative to have support to your left to hold the bulk of the quilt. If you don't have this, you always have some weight of the quilt interfering with motion. An ironing board lowered to the level of your cabinet, placed to your left, works pretty well. Or get an inexpensive table from Sam's Club to hold the quilt.
For the portion of the quilt under the machine arm, I found that loosely accordion pleating works *much* better than rolling the quilt or stuffing it any which way under the arm.
Another big help is to split your batting into 3 parts. You quilt the middle portion first, reattach batting to one side and quilt that, then reattach batting to other side and quilt that. It reduces the bulk under the machine arm and also reduces the weight of the quilt while you are working on it. There is a methodology for doing this, so definitely research it before trying.
There are other methods for quilting with less bulk too. You might want to get this book:
http://www.amazon.com/Machine-Quilti...dp/B000NNGZJE/
Edit: Also, are you working on a large flat surface? If not, that could be your biggest problem. Here is a link to Youtube videos that show how to make an inexpensive flat table for quilting (but you still need support to your left!):
http://www.youtube.com/watch?v=g14govA4pIM
http://www.youtube.com/watch?v=yAS25v3ZTk0
http://www.youtube.com/watch?v=A0lk7UBQgZY