Watch the Analyze The Harmony online guitar lesson by Jon Herington from Ear IQ: Reactive Improvisation

If you want to improvise well on chord changes, it's critical to develop the ability to quickly analyze the harmony and memorize the form of a song's unique set of chord changes. This involves listening to every note, discovering the unique combinations of notes that are occurring at the same time at every moment of the song, and reducing all the details into the simplest possible manageable, memorizable form. If you can master this, the following sections will be much easier and more rewarding.