If you want to do custom graphics, have them transferred to a transparency (any Kinkos can do this for you). Have them print it
in reverse, so that when you place the graphic against the body, it's printed on the side that will touch the guitar. Use an adhesive that's specifically designed for mounting photos (3M makes a good one, it runs about $12 a can at most office supply stores).
Trim it so that the picture has about 1/4" of the transparency surrounding the graphic. Then, using some 600+ grit sandpaper or some 000/0000 steel wadding, rough up the area you are going to apply the graphic to. The 3M spray adhesive will not stick to a completely finished surface.
Apply the adhesive to your graphic, stick it to the guitar over the area you roughed up. Use a credit card or something to smooth out any bubbles. Be careful not to scratch the guitar in doing so. If you have any adhesive overspray or mess to clean up, a little Zippo fluid will clean it up.
Then, get a good
clear coat (Lowes or Home Depot sell a couple decent sprayable clear coats) and start clear coating the decal. Deft is a good clear coat. Lightly build up coats of it - do not use any heavy coating.
That should do the trick.
-R
