[Joe]

Apart from using curtains, switching lights off indoors, and general things to minimise inside reflections on the glass, I've also found in the past that a nice big rubber lens hood to almost 'sucker' onto the window helps.
On a slightly different tangent, but reflection issues related....I traditionally blacked out the white writing on the front of lenses. Fortunately, more recently some lenses (particularly Canon) have that white text on the outside front edge of the barrel now. It's something I found years ago affected my pictures (not sure how much it does with my current gear), where I narrowed it down the the white text being reflected back on the protective filters mounted on the front of the lenses!....I guess the same applies when the lens is up against glass, even if you don't use protective filters.
Black marker pen that I know I can wipe off without wiping off the white text too is a good idea, I'm personally not the biggest fan of using messy tape.....particularly if you think you might be re-selling the lenses at a later date?