When I go to Goodwill, garage sales, antique stores etc. these are the types of things I usually look for:
Vintage (or vintage looking) trim, lace, yarn, crochet thread etc.
Interesting and unusual aprons (I love aprons!)
Pretty greeting or post cards that I can use for crafts
Anything with Rosie the Riveter (haven't found any yet)
Books for my son (educational as much as possible)
Books for myself (I always look at the books. I love to learn about history.)
This is one example of milk glass. Isn't it beautiful! This pic is from Flickr. Sadly, I don't own this. You can see one vase in my craft room pics though.
Hankies (ladies handkerchiefs)
Doilies (I make doilies but I get ideas from the ones I see and sometimes buy)
Those are the things that are usually going through my mind as I'm shopping.
What sort of things do you look for?