The signs I believe in that have happened to me and the only thing that has given me proof are thinking of someone out of nowhere and them contacting soon after.
I don't personally believe in dreams, I dreamt of someone and had a very specific dream of them and it never manifested. So I always discount dreams, but that's me. The same with seeing things and thinking it's signs, I feel like I did lots of that because I wanted to see the signs or it was coincidence.