One of the biggest challenges for me when I'm starting a new crochet design project is figuring out the proper gauge and really how many chain stitches I'm going to need in order for that first row to be the right width. Well, yesterday, I had an insight and wanted to share -- use the chainless foundation technique to figure this all out! Chain 2 and make a single crochet stitch in the second chain from the hook. Then, insert your hook into the loop at the BOTTOM of the stitch you just made. Yarn over and pull through a loop, then yarn over and pull a loop through the first loop on your hook, yarn over and pull a loop through both loops on your hook.* Repeat until you have the desired number of stitches, then measure to see the width and adjust accordingly. If you don't like the way the bottom of the work looks, then at least you'll know how many chains to make in order to make the number of stitches you need to get that width again! Hope this helps!
*The chainless foundation can be performed with the double crochet stitch as well -- yarn over before inserting your hook into the loop under the last stitch made. Yarn over and pull through a loop. Yarn over and pull a loop through the first loop on your hook (you should have three loops on your hook), then yarn over and pull a loop through the first two loops on your hook, then finish by a yarn over and pull a loop through the remaining two loops on your hook.