So I got my new guitar, and like a fool started fiddling with the tuning knobs. Pretty soon it sounded like a mess.
Android to the rescue. After trying out about 6 or 7 apps, I found Guitar Tuner to be the most user friendly.
Its free, and the display is easy to read and work with.
When auto mode is on (which is the default) it guesses which string you are plucking and tells you whether to go up or down to tune it. This works when the strings are nearly OK and just a little bit off.
If you've messed up some of the strings completely, like I had, touch one of the string notes (EADGBE) buttons on the app, pluck that specific string, and tune it individually.
Even as a novice, I had my guitar tuned in no time. Great little app.