I keep seeing lots of long-time #fediverse users saying 'don't favourite posts it does nothing' but actually when you favourite my posts it makes me smile and I'm sure I'm not the only one.
@djdellamorte I favorite (many) posts that make me smile, or are interesting, to let the author know that I read and enjoyed them.
I boost (some) posts that I think other people really should see.
I bookmark (few) posts that I want to be sure to find later (maybe to read linked articles in depth or reference elsewhere).