Start with the melody - that's what Sonny Osborne says. Learning to play the melody and "play the syllables" is very important when learning a tune. It helps with memory, understanding timing, phrasing and more. Bonus points if you sing words while playing. That will help your memory and improve your musicality even more.
This melody follows the verse lyrics. In jams and bands, it is usually most common for the instrumentalists to play their solos using the verse melody and chords. When you are trying to learn to play lead, this is the most important place to start.
Check out the licks to use some simple 3 finger style banjo tricks to add flair and fun to your arrangement. The licks feature pinches, fill-ins(bum-ditty), and basic rolls that are based around the melody.