Transcribing used to take 60% of my practice time the other 40% was playing over my favorite recordings and learning new tunes. Personally I like first to listen in repeat the piece of music I want to transcribe. Then I start singing the solo or theme over and over until I can match the pitches, rhythms and articulations perfectly. Lastly I will learn the piece on my harmonica, slowly, phrase by phrase.
I recommend to use a software in order to slow down a recording such as the Amazing Slow Downer