I frequently run into issues with not only my own quilts, but also those that are given to me to quilt on the longarm. These posts go through some of the problems I have seen with tips on how to handle them. See also the page on Quilting Basics.
Reworking the Cottage Garden Quilt – Taking a quilt completely apart because I hated the quilting, then requilting and rebinding it. Here is how to skin a top from the backing.
Fixing a Mistake in a Finished Quilt – Realizing there was a piecing error in this quilt after it was quilted and bound, this post will show you how I lifted the incorrect patch placement, re-stitched and then requilted it.
Loading the Longarm – some of the things that I encounter with charity quilts, and how I deal with them.
Dealing with Quilt Issues – things longarmers most complain about
Fixing More Wonky Quilt Problems – more of the things that come up charity quilting and how to handle them
How to Use a Towa Gauge – solve 99% of your thread breakage with this tool.
QOV Quilt – Fixing fullness with steam after the quilt is on the longarm.