From a practical perspective, teaching yourself guitar may be the only option. Guitar lessons cost money. If you’ve just scrounged your pennies together in order to afford a decent starter guitar, you may not be eager to throw down another twenty bucks a week or more. Compound this with the fact that most guitar instructors have their own methods and will teach you at their pace, not yours. This makes sense from their standpoint, but it could get a little frustrating and expensive from your point of view.
I have checked out Justin's site and found it to be comprehensive and informative. I have always felt that learning about music and especially music theory applied to the guitar, is helpful in finding your own unique voice on the instrument and expanding your creative horizons. Along with his insight into teaching and his fantastic abilities on the instrument, Justin has created a powerful go-to-place for anyone interested in exploring the instrument to their potential. Just don't hurt yourself.

So anyhow, both GuitarTricks and JamPlay are great sites, it all comes down to you, the student. If you are diligent and dedicate enough time and practice to it, you’ll succeed either way. The reason I recommend GuitarTricks to beginners is because it gives them one less chance to sidestep and wonder around looking at other teacher’s lessons when things get a bit harder. That’s what a lot of people do on my site.

Berklee College of Music was founded on the revolutionary principle that the best way to prepare students for careers in music is through the study and practice of contemporary music. For more than half a century, the college has evolved to reflect the state of the art of music and the music business. Berklee serves distance learners worldwide through its award-winning online extension school, Berklee Online.

Of course, this top-down lecturing is all very abstract without examples. Let me give you the worst case scenario. My school talent show, 2008. Two friends of mine performED an ambitious but utterly inappropriate Metallica cover in front of the other students, their parents and the faculty. It was excruciating. Although the solos (presumably the only thing they had bothered to practice) were technically flawless, the whole song was undone by their terrible rhythm. The timing of the song became displaced, the chords were so badly fingered that it was difficult to hear the riff and consequently the whole performance fell apart. They looked like morons. They had sacrificed learning basic rhythm and paid the price. Make sure you don’t do the same.
4.) Check the guitar’s string height by pressing down on the first, second, and third fret. You should be able to do so with minimal effort. Come to the 12th fret and press down. The distance from the top of fret to the bottom of the string should be no more than three times. If it is five times, the guitar may have a warped neck or too high of a bridge.