A week ago I refurbed the 15" alloys on my aging VW Bora with the standard (flaking) silver paint. Got all four done in a day and was pleased with the results, especially with new VW centre caps. Having done this a couple of times before the two important rules are to take your time and not shortcut the work.
After removing from the car (I did two wheels at a time), each wheel was given a serious clean to get the mud, oil and grime out, before sanding with 800 and then 1200 grit paper as per the previous post. Then they were masked up. The masking tape is thin enough to get between the rim and the tyre, so I cut a circular hole in a large cardboard panel to lay of the top of the wheel. If you cut this slightly larger than the alloy wheel diameter, then your masking tape can cover the gap between the wheel and the cardboard. I made two of these so could paint two wheels at a time - speeds your day up.
Next the wheels were sprayed with white primer. This really helps the paint bond, obvious as that sounds. I used even, left-to-right strokes (don't zig-zag or spray in circles). Then they were left for a couple of minutes between coats.
Then build up the paint, in my case silver. Don't spray it too slowly or thick that it runs; this will be a pain to sort out. Finally, I added a lacquer top-coat. This is where, in my opinion, patience pays off. You apply a couple of coats as normal and then subsequent coats get slower and slower strokes. I find this builds up the lacquer into a nice shine without it running.
The Halfords stuff I bought was more than up to the job and including sandpaper and masking tape it was around £25 all in.