The most important thing you must do when learning how to play guitar is practice! You're learning new things by doing the work, here, this is playing guitar, simple. By saying that, i mean playing guitar, not pulling the strings with no reason at all. And when you're practicing, there is one thing you should never do and that is you must never, ever do it in a rush, just take your time and the results will come.
The next important thing is you need to get organized while learning new stuff. You need to start at the beginning and start playing simple chords and stuff like that. When playing guitar, just remain as relaxed as possible, relieving the tension off. The tension in your body prevents you from playing correctly and this is wrong way.
Practice every day, every single day, if that is possible, if not, just try doing it in some order, just never quit for a longer period of time and then start again. This is not the way to learn how to play guitar, it does no good for your playing. So, get habitual at playing guitar and i can almost guarantee, you'll learn fast.
The other important thing, when learning how to play guitar is, you need to play the music you like. Don't start to play songs you don't like, because that will only get yourself frustrated and consequently get the wrong results or no at all. As what i'm going to say next, may sound stupid for some, believe me, it is not. You need to write your goals down, like what do you want to achieve, how much time are you willing to invest into learning to play guitar and why you want it!
When playing guitar, always use a metronome. It can and will improve your timing and make your playing sound better for sure. When finding a problem, try first to overcome that problem, don't rush to some other stuff, because it gets boring or start doing other things just because you don't like the things you need to learn. When you become persistent and learn how to play guitar the right way, the results will come and you could soon realize you are playing better and better, and that's probably the reason, why you even started to learn how to play guitar the right way.