I approach teaching the guitar from a skills perspective. That is, whatever songs or style of music you wish to play it will incorporate a range of skills that require at least some degree of attention to allow them to be used fluently within the music. These skills are not just physical on the instrument but also musical. Some are absolutley core and needed irrespective of whatever music you want to play, eg; being able to play notes and chords correctly and change smoothly between them; being able to feel the beat of the music and play in-time to it; being able to play 8th and 16th note rhythms; right-hand strumming technique; listening whilst playing; remembering sequences of chords/notes and understanding song structures; being able to 'perform' a short piece and make it 'musical' rather than just stumbling through notes in the correct (or even incorrect!) order.
Other skills are more specific such as lead guitar techniques like string bending, hammer-ons and tapping, also perhaps fingerstyle, speed technique, understanding 'jazz chords' and improvisation and these will be more or less important to different students and their personal tastes.
I typically try to isolate specific skills and work on them with brief exercises in tandem with using songs that allow the student to develop those skills in a real musical context. This is with the goal of getting every student to a point where they can play the music and songs that they want to unhindered whilst sounding musically fluent and with the knowledge and ability to address any difficulties that may arise along the way.