Here's the best way I have found. First gently rough up the guard with very fine sandpaper or a fine scotchbrite pad. Get some RIT fabric dyes from WalMart or whatever you have across the pond, its easy to find here in the US. I use a mixture of dark green, yellow and brown, weighted heavily towards the green. Mix it in a shallow pan large enough to submerge the pickguard. Slip the pg in and shove it into the oven at 200 degrees (thats degrees F, are your ovens metric?) for about 25-30 minutes. You can check it periodically until you get the color you like. Make sure to rinse thoroughly when you are checking because most of the color will rinse off. The goal here is to end up with a nice looking mint green color. Next, mix yourself up some of the yellow powder with a little water. A thick liquid consistency is perfect, you want it almost a paste. Take a cloth and rub the yellow (which should look dark orange) around in key areas of the guard. Look at some pictures of old guards for guidance. Wipe a little on and then wipe it back off, repeating if necessary, until you are satisfied with the look. Here is one I just finished. Don't shoot, I know it is a strat, its all I had around at the moment. It started as an ordinary MIM bright white guard.
