I looked around the net and found plenty of tutorials for cloth napkins. I still couldn't resist adding another. This also shows my work-flow, which is just how I do things.
First, pick out two coordinating fabrics. For my napkins, I just went through my stash and started pulling fabrics out, then, I pulled out some coordinating fabrics. Not everyone has a big stash, so if you want to make a nice coordinated stack of six to twelve napkins, you'll need two yards of fabric (one of your focus and one of your coordinating fabric). I say six to twelve, because you'll get more napkins out if you cut them smaller. I'll put some math at the bottom of the post so you can decide how to use that fabric.
Okay, now for some math.
One yard of fabric is approximately 36" x 42" (I say approximately because the lady at the cutting counter may cut your fabric really close to the 36" line, and do it poorly, or she may cut closer to 37" and cut rather straight. This is why pressing and folding accurately is important. If you're really worried by it, you can always buy more fabric.)
This will yield six napkins cut at 13" x 13", finished size 12.5" x 12.5" (This is my preferred size, but feel free to pick your favorite.)
Or, this will yield eight to 12 napkins cut at 10" x 10", finished size 9.5" x 9.5" (NOTE: you have to be very careful with the cutting for this one, since the fabric is 42" or so wide, one little mistake and you won't get four napkins across the width-of-fabric.)
If you use the tutorial, please share your results. I'd love to see what you've done!