basting spray is the best invention. Goes on like spray starch holds your quilt top firmly to the batting and nothing moves.

I agree with all previous suggestions, so won't repeat them here. Here is a good review of various basting methods & links to video tutorials: http://thecuriousquilter.wordpress.c...g-away-again/.
I also like Sharon Schambers' video on basting: http://www.youtube.com/watch?v=bhwNylePFAA.
Another product many people swear by to prevent thread nests on the back of quilts is to use: "Magic Genie" bobbin washers. These are just a flat silicone washer (think like a 1/2" diameter round disc) of flexible but stiff material with a hole in the center. It goes into your bobbin case before you put in the removeable bobbin full of thread. It helps stop the bobbin from over spinning & leaving too much thread unwound in the bobbin case. They can be found online @ quilt shops and even ebay. You would want the regular for a home machine, not the "Long-arm" ones.
Best wishes, Cathy

I tape the back to a flat surface, then pin. The first few rows (I quilt diagonally) I pin in the seam with the head of the pin so I can remove them as I go. No basting, no walking foot, and go slow.

Before I start, I practice with a small sandwich till the tension and stitch length are just right.

Don't forget to check the tension on your bobbin case. Sometimes the bobbin is the culprit.

Make sure your quilt is supported. Do not let it fall over the edge of your sewing table. That causes the back to move faster than the front, thus the puckering. In quilting, gravity is not your friend!

When the back can move directionally as your has it is an indication that your basting is not taut enough.If you are basting with thread, try to make it even in each direction. I prefer spray basting very lightly and on some quilts, do anchor stitching in the ditch to keep the quilt square.If these are done with dissolvable thread, they are easily removed.
As for the tension, try adjusting on a practice sandwich before you get going on the quilt and you may have more success. All the best with the adjustments.
(Also make sure you have your quilt supported on a flat surface, and not dragging against you or hanging down from the machine).

I always had this same problem until I bought a walking foot for my machine....like magic!!...no more puckers on the back.

A lot of good advice! I will use them as well.

This happens to me when my bobbin is not loaded properly. You might reload it.

I was machine quilting not with a walking foot, but with a free motion foot and forgot to lower the pressure foot. When I looked at the back it appeared the stitches were just sitting on top of the fabric and when I pulled on them, they pulled out very easily. When I restitched and made sure the pressure foot was lowered, it all stitched fine.

Yellow Rose

I agree with her spray baste and hold very tight all 3 layers I used to have the same problem then holding it very tight solved my problem also..