Just smile and say "thank you." Nothing else is required.I don't know how to receive gifts. I get all squirmy when I'm given a compliment, even. Random acts of kindness? Ugh. Those are the most difficult to process.
As for Christmas presents, I received one I wasn't expecting. So now I have a new adult coloring book (one of flower garden-type pictures), some chocolates, and a stuffed animal that I think is supposed to be a donkey wearing a Santa hat.