The guitar is a remarkably hackable instrument for a million reasons that will be revealed to you as you spend more time with it. As you go along in your journey you’ll find a million shortcuts and fun ways to learn fast. I’ve rarely heard any of this stuff from guitar teaches, so beware, trust your instincts, and learn from people who can show you where you want to be.
The teen and tween years are the make or break years for most people, in deciding whether they’re going to stick with a childhood hobby or interest, for life. As you go through puberty, and begin preparing for life as an adult, and responsibilities pile on your plate, the first things to go tend to be the personal interests you’re passionate about, because they don’t pay the bills. Also, because they’re not an official part of your school curriculum. In other words, what was once a must-have becomes a nice-to-have.
Learn the difference between chords and single notes. Chords occur when you play two or more notes on different strings simultaneously to create one unified sound. These are what make up the "rhythm" portion of acoustic music. Single notes are used more for solos and occur when you play a single note at a time. Both are skills that you must become proficient in when learning to play the acoustic guitar.
As a beginner, it is best to avoid making a pawn shop, flea market, or yard sale purchase unless you are shopping with somebody who has experience in purchasing a guitar. Having never purchased a guitar, you may not know what to look for in terms of damage or guitar quality. With that being said, a local music retail shop is your best bet. You may also shop online with a reputable company, although be sure to review the business’ return policy.