For the first several years that I've been trying to learn the mandolin, I focused on memorizing melodies and practicing chords. Lately, I've been struggling with playing 'by ear'. Mostly, I've been listening to a melody and trying to recreate it on the mandolin. Sometimes, I will put it in tablature and practice it - Other times, I'll just try to play it during the course of a song. This seems like a natural progression from practicing from paper all the time.