I'm not sure how well I'll do explaining this, but here goes....
First, what I'll generally do is put the blade on a flat platen and sort of sharpen it. This will show me where any unevenness is, and really highlights the thick and thin parts of the blade.
Then, I'll take it to the wheel. I usually use an 8-inch contact wheel. This works for all but the largest wedges. A larger wheel will make a flatter blade, but I really like the results I get on an 8-inch wheel. It will maintain a single concave cross section, but does a good job of thinning out the blade. I've found they shave better afterwards to me. On a regrind, I'll grind from the center outward, taking the unevenness and wear out of the blade. My belt progression is 120-220-400-500-600 cork-800cork-600 cork loaded with emery compound-800 cork loaded with green chrome, then to the buffer (oh, and be careful...3 days ago I lost the tips of 2 fingers to a blade/buffer/hand meeting). Check the blade often to make sure it's lying flat on a flat surface as you're regrinding. A lot of this is done by practice and feel, so some of it I suck at explaining. That initial bevel created on the flat platen will show you where you need to grind the most, and gives you a witness line to show you how deep to take the grind to achieve an attractive, narrow, even edge bevel.