Power chords; The metal in Metallica, the "eleven" in Spinal Tap. The racious in Ramones, the sex in the Sex Pistols. Power chords are ubiquitous, even in pop music. Knowing how to play them gives a person an advantage to playing the far more perplexing, if not maddening, barre chord. Power chords have their place in history, and just like everything in guitar, they can be tricky. The good news is that there is a way to hack playing them. Hack, as in "workable, approachable solution." This hack will show you a neat way to make power chords beatable, if you don't have much experience with them yet.
The frets on the guitar get smaller as you approach the actual body of the guitar; The closer your fret is to your body, the smaller it gets. One problem a lot of people have is that their fingers don't like to stretch or compress with the width of the frets. Usually, their third and fourth fingers do not stretch or compress easily enough to play the chord clearly.
The Hack:
Place your eye on the index/pointer/first finger, and position that first. Paying close attention to the position of the first finger means you get the advantage of securing the lowest, and probably most important, note of the chord. Make sure to do that before futzing with the other fingers. The result? Your third and fourth fingers (ring and pinky finger, respectively), will learn to adjust. Once again: Eye on the index finger.