[Vizcaster]

First off, you need to know if the product is supposed to be wet sanded. I found out the hard way that the water based lacquers I use are not supposed to be wet sanded until after they fully cure, which means you shouldn't do it betwen coats.

Assuming your product is safe to do it on, you use a lubricant like water (maybe with a drop of dish soap, again assuming that doesn't contaminate the finish or create problems for the next coat). You'll need wet-dry sandpaper that doesn't fall apart when wet, and that also means a rubber sanding block instead of wood). You can probably start with 600 (400 would only be necessary if you need to cut back a bad defect, but that can also be done with a woodworker's cabinet scraper or a utility knife blade), and go to 800 and 1,000 if it's the final coat and you're going to be buffing. Dip the sanding block in water and start sanding, you'll start to get a slurry of finish. Wipe it away with a rag or sponge to keep things neat. You'll see little craters and divots of grain or just plain areas that are unevenly coated with finish. The more you sand and get the finish level, these shiny spots will begin to disappear. Then you know the finish is mirror smooth and can be buffed out without looking like a waxed tangerine (ever see an $85 paint job on a car?). The main advantage of wet sanding is that you don't have fine white powder everywhere. The secondary advantage is that the paper will not clog as quickly (not that it doesn't happen). Wet sanding really has nothing to do with making the cutting action more gentle or finer -that's only a function of the paper grit. The main problem is that you cannot see the scratch pattern and you won't know whether you've sanded enough or too much - unless you're confident enough to do it blind, by feel and touch (actually run your hand over the surface, but again it's harder to tell when it's slippery wet).

I have abandoned wet sanding for the most part, and have found that real good quality papers make a huge difference. Either Klingspoor (available online directly and from woodworking catalogs) or the 3M gold (from Stew Mac sold by the sheet) papers are excellent for dry sanding. There's also something called stearated abrasive where a soapy lubricant is added to the paper so that it does not clog when sanding finishes, and actually most sandpapers have some degree of stearate in them. I don't use these because they can be a problem with water based topcoats, but they are helpful when you're doing tradional solvent based finishes.

Bob Flexner wrote a good book on wood finishing that takes you through the steps; he also updates it now and again to explain the various types of finish technology that has come along and demystifies the whole thing. I believe it's a Taunton Press book. Once you've digested that book, you'll notice that you've already read most of the tips that show up in the finishing columns of the woodworking magazines.

Oh, and you have to share with us what color Krylon you chose, because you'll get some people weepy if it's Surf Green...