I've taught various instruments - but not the guitar.
However, I think there are a few things I can bring to the table;
Every student is different. Duh.
Easy to forget, though - when I first taught the piano, it was because a friend of my mother wanted her sons to learn - and then their mothers' friends wanted their children to learn, and so on.
Most of the children came from similar backgrounds, were delightfully serious about learning, and truly wanted to do well, so they actually practiced at home and showed off their prowess as the lessons went on.
With these children it was easy to start right at the beginning with absolute basics, and going through technical stuff like scales, arpeggios, aural and even music theory just seemed to make it more interesting for them.
Then one day, a boy turned up who was more interested in football and playing games than the piano - he was co-erced into it by his mother, who wanted him to be like his friend (who came to me for lessons and had attained a distinction for Grade 3).
I found that by adjusting my own style, listening to him chat about football for a while, then trying to relate what he'd told me to music helped - and I developed a series of games based around the technical excercises, including making some of them sound like songs he liked.
I then got another boy who had "future drop-out" written all over his face. Again, it was a question of adjusting the style to suit, finding out what he wanted to learn (which was not the "boring" curriculum stuff, but pop music). He did eventually become a kind of drop-out (he stopped his piano lessons and I started teaching his mother instead!), but he NEVER lost his love of music - he bought a guitar and joined a band, and, to the best of my knowledge, is still playing. Last time I saw him he thanked me for getting him into the technical side of music, which he felt helped him to learn the guitar quickly.
The thing here is that everyone learns in their own ways, and at their own paces - never hurry a "slow" student.
If they're not practicing, give 'em hell though - if they stop lessons altogether as a result then they simply don't have the commitment it takes, so don't feel bad about it.
What I also found, however, is that students vary in their reactions to how you correct errors - you need to be very sensitive here, as some really don't like being told that they're "getting it wrong", even though they'll be too polite to say so.
All the older teachers I had, particurlay an Opera singing teacher I visited frequently at her home in Victoria, liked to "sugar the pill", as in "That was very good, now, if you try it like this, does that sound better to you?".
This technique, while very simple, has the added benefit of allowing the student to try different methods and develop their own musical approach - while there are a whole load of accepted techniques that are "right", there are nuances and subtleties that musicians can bring that reveal their own personal touches - and in my opinion, these are to be encouraged, where they don't interfere with "correct" technique.
Final tip for now is resist the urge to "show 'em how it's done".
Students tend to copy their teachers - that is almost inevitable, and once in a while, it's good to let them know who the boss is - why you're the teacher and they're not, and sometimes, a particular passage simply requires clarification.
Music is a very personal thing - it is initially a method of communication from artist to audience. When the artist communicates genuinely, then there is feedback, or resonance, and a kind of dialog is set up. Showing someone exactly how to play a piece of music is like telling someone how to give a speech - it can be done, but the end results tend not to be as convincing as when the speaker has their own, gripping style.
This is all top of the head stuff - hope it's helpful.