This hint is for the really green guitar players:
Many people buy guitars and either find a teacher or a friend to show them a few things. Often, this teacher or friend will immediately start teaching this musician in the making about keys, music notation, modes, scales, and theory. Then this teacher of friend will take a breath and start into resonance, and the harmonic/overtone series.
The new musician will go home and start playing his/her scales, learning his/her chords, and studying his/her music notation.
This poor soul realizes that all of this is boring and difficult. S/he gets intimidated and overwhelmed and quits playing.
Musicians who are just starting out should play what they like to hear. They can worry about the technical aspects of it later. All a new musician needs to know is how to read chord diagrams. Initially, they can pretty much sort out the rest on their own.
I'm completely self taught. I can remember working three hours a day, seven days a week for about two months on "Stairway to Heaven". I was twelve at the time. I never play the song anymore (I can't even stand to listen to it) but I can still remember how to play it.
The important thing is to pick up the instrument everyday. Get used to the way it feels, play what you want, and don't time yourself. Above all, play. If it was supposed to be work, they wouldn't call it playing.