Don't make the mistake I did. I did the old "stand there, hold your arms at the side, put your palms flat, and how ever high your palms are, make it that tall" trick.
Well, it's too high. Subtract a 2 or 3 inches. That way, when you're planing, you can lean into it, and there WILL be times when you'll want to pull up a stool and sit to work on something. You can always make it higher, but it's hard to make it lower...
Thanks,
Bill