Watch the Troubleshooting Tips online guitar lesson by Rich Maloof from Acoustic Guitar For Beginners

Here are some of the most common problems that trip up new players. Don't let 'em bring you down. You'll be surprised how quickly you can practice your way right past these stumbling blocks.
NOTES ARE MUTED
Build chords note by note. Don't play over fretwire. Change the angle of your fingers to the fretboard.
FINGERS HURT!
Don't press too hard but do expect calluses. Once they form, you'll be able to play without pain. Only your fingertips should feel it.
HARD TO SYNC STRUMMING HAND AND FRETTING HAND
Think ahead - know what chord you'll have to change to next, and when it's coming. Get your right arm strumming steadily and soon it will be on autopilot. Practice!
CAN'T PLAY IN STEADY TIME
Always practice new material slowly. Play along to a metronome, and play at a tempo that makes it possible to make the chord change in time. Also, look for common tones and pivot points.
BROKEN STRING
Have your strings replaced by a friend or at a local music store. If you feel like experimenting, there are dozens of articles and videos online showing how to restring a guitar. But expect to ruin a few strings or poke a few holes in your finger before you get it right.
TUNING
Get yourself a digital guitar tuner, which will show you with lights and/or meters whether you're on pitch. The video here shows you how to get a string in tune.