I always do a test quilt swatch and start with my top tension on the factory setting. If I have eyelashes on the bottom I slowly increase my top tension a couple of numbers. If I still have eyelashes on the bottom I fiddle with my bobbin tension until I get a balanced stretch on my test quilt sandwich. Moving your bobbin tension is not scary if you take a picture or make a note of the screws position before starting. You can turn the screw back for regular sewing later if you know where it was orininally.