Sign help

[mybuddyishot.livejournal.com]

my friend is making a sign for his business to stand out by the road so people will know his store is in the plaza. I am going to be painting it so my question is, is acrylic alright for this job? Is it waterproof/sunproof? Can I use a sealer over it or would it be best to find some other kind of paint? The sign is made of wood too if that has any bearing on the type of paint.