Here is a good article on tips for wood finishes. The key is a clean surface and a good sealer. We are having good results with Jamestown Distributors TotalBoat Wood Sealer and Gleam right now, and have always liked Pettit Z-Spar. Whatever your favorite, or what is available, follow the directions for the sealer, which may just be a first coat thinned with mineral spirits.
How to Apply Wood Finish