I tend to use alot of 'Japlac' enamel - It's easy enough to get hold of, (All the big diy. stores carry it) and suitably primed gives a lovely finish, Then a very light rub-down with fine steel wool and finish with a couple of coats of good polyurathane varnish, (Matt or silk finish for preference) to keep the damp out. For larger areas I use 'Dulux weathershield' same suppliers, if applied following the instructions it's guaranteed for six years! - I think the short answer is, any good quality will do, so long as you don't apply it too thickly, (Build up a number of thin coats, rubbing down lightly in between) And for lettering, thin to a usable consistency and use a good quality, long bristle lining brush, again building over several thin coats. Hope this helps
