My preferred method has evolved over the years - and the exact method depends on how good the final result needs to be (e.g. display model vs. a frequent flyer). However I'm anal enough about it that I always do at least basic wood sealing and filling body tube spirals even for 'disposable' flyers.
My current primary method is a layer of Elmer's white glue (i.e. "Glue All"), sand, then a coat of thinned Elmer's Wood Filler, sand, then at least two coats of sandable primer (different colors). I like Krylon Industrial Tough Coat sandable primer.