While researching Key Signatures I found this very helpful diagram to help me remember how to figure out what key a song is in when reading sheet music.
Another useful tool I found is called the "Circle Of Fifths." It is used to decipher the precise number of sharps or flats in any given major scale.
I read in one of my books that one of the best ways to memorize the order of sharps and flat is word association. "The sillier and weirder the better,' says the Hal Leonard Corporation.
Order of Sharps: F, C, G, D, A, E, B, F
(Fat, Cats, Go, Down, Alley, Endings, Boldly, Fighting).
Order of Flats: B, E, A, D,G, C, F
(BEAD Games Come First).