Well, for starters, pick one jar first. Perhaps the plainest looking. And order sample packs of wicks, most suppliers sell them. You can always go back and order larger packs of the correct sizes, and you'll have the extras in the sampler pack for trying out on different sized jars. Keep in mind the larger jars burn for a longer time so will take a little longer to test. Keep doing your research. Lots of good stuff on here, as I'm sure you've already found. Just give it a try and go from there!