The first thing I do is to check the batting package to see how closely your quilting must be for the batting to hold up to regular use and washing. For cotton batting that usually means that there must be quilting at least every 2 inches throughout the quilt. Next, if I'm doing blocks I need to decide on a block patter than complements the block it's self then I add in borders that compliment the block pattern. Sometimes you can decide by the fabric it's self, say for an autumn table runner you can pretty much know that leaf motifs will be appropriate. One other thing that I consider is the seriousness of the quilt or the novelty of it. I wouldn't ever do Fluer-d-lis on a 30's print quilt for example. Background fillers are another thing to consider. If you want the blocks themselves (intricate piecing) to really stand out, I often will do stitch in the ditch on the blocks and fill the background fabrics with small motifs like stippling, meandering, circles swirls etc. Hope this helps but if not just post a pic of your quilt and folks will be happy to tell you what they would do for quilting it.