The wood to be stained must be dry, clean and free of any oil, grease, fingerprints or other surface contaminants. Solvent washing is the most effective method. Fill any surface imperfections with wood putty or stainable wood filler.
Always sand and dust between coats to ensure a smooth surface. Windowsills that are exposed to a large amount of UV that requires a gloss finish should use #1130 Spar Varnish in place of #1120 Gloss Varnish.