DO NOT GIFT YOUR FRIENDS RANDOM STUFF!
The trick is not to just gift anything to everyone, but wait to see who has requested materials from you. It's a bit more involved this way, but you help your neighbors a lot more.
By the way, if you don't know how to request materials from your friends: Click on a building you are constructing. When it tells you that you need a certain material click to ask a friend. It's that simple.