i hope this helps a little bit.
first of all you have to get a good guitar player and that doesn't mean palying songs directly. you have to have first your muscle memory.
This means by playing your scales over and over again, and i mean over and over agian until ti is getting boring , but indreclty your muslce memory will go int o your head , and when you hear a song or hear a lick at smome point , according to my opinion , you recognize some notes or chords, or maybe you are just below or up the note , but you will recognize it , and then after palying thousand times your scales over and over again, you muscle memory is so good , when you hear a chord in a A minor key f.i., you atomatically find a note upon your scale , and that is most of the time one of the root notes , and hey you are starting.
Hey believe me , i play now for 30 years , and that is the only approach . every note falls in a scale somewhere, but your muscle memory has to be good ! otherwise you will hear a song or a lick in your head, but your fingers don't know where to go
Good luck , believe me this is the only way
