I don't set out to memorize off the bat.
If I know the melody of a song, I play by ear.
If I don't know the melody, I write down enough (key signature, lyrics, chords, reminders, notes to myself like "medium swing," "repeat", etc.) so that I can play it from a sheet of paper.
In either case, after enough repetition, I don't need the paper.
Yes melody and lyrics can certainly be effective triggers