It's not too hard to do actually.
Mix some washing up liquid with warm water, and leave some 400grit, 600grit and 800grit wet and dry in it for about half an hour while you strip the headstock of strings tuners and string trees.
Start wet sanding over the decal with the 400 grit, don't dig in, you don't have to, you're removing layers of topcoat not rust, keep rubbing until the decal starts coming away. Once 90% of the decal has been taken away, switch to 600 and do the same thing until everything is gone, then give it a light rub down with 800grit, clean it, leave it to dry. Over here, i leave everything to dry overnight once i wash it because apart from two months of the year, it's not hot enough, and there is nothing worse than spraying, getting cracks, and having to do it all again.
Now, you're headstock is still sealed, and it's already nice and flat from the 800, so apply the decal with water, leave to dry, then topcoat it, light to medium coats, 15 minutes apart, until the edges of the decal disappear, one or two more coats and you're done, the dullness from sanding will also be gone.
Sounds alot of work but it really isn't, from picking up the 400 to putting down your 800 and cleaning the thing will take 10 minutes max, and that's if you're a noob. Leave your topcoat to dry for at least a week before you risk putting the tuners on, you'll get fingerprints in the finish otherwise, and don't polish it for a month after.
