It helps a lot to be able to recognize if something is on a standard diatonic scale & chord progression, or uses chromatics and modulations. It greatly reduces the search space if you know the notes and chords you're trying to find are out of 7 choices rather than 12/48+.

If you can't recognize that yet, finding tablature or sheet music can help you tell for a given song, before you go banging your head against a wall trying to figure out something that is musically unusual.