Garages here can get very hot in the summer. I would only store items impervious to heat and humidity there and nothing at all in the attic. Use only metal enclosures in the garage, nothing made of particle board that invariably warps, molds and attracts bugs. Clothing, electronics, photographs and art supplies should be kept in an air conditioned space, perhaps locked in a coat closet, pantry cabinet or walled off half of a bedroom closet. Toss in a couple of borax type roach traps. Regardless of what you store here while away, take all true valuables and vital documents with you.