Hey Arnie,
The first thing I do is learn the chords, because rhythm is totally different than lead. You have the right idea about splitting it up into parts, learn it from the beginning. Start with the progression on the intro, then the verse, chorus, solo. You also want to pay close attention to the order in which these come. Once you learn the chords, and the progression, then you can move on to figuring out the leads. Since you'll know the chords, it can give you an idea of where the leads are being played. I hope this helps you, and let me know if you have any other questions.