CTG-10 Clip Tuner : Useful and versatile

Incredibly good money for value purchase.

I got this as part of the bundle of my first acoustic guitar and used it constantly ever since (> 6 months). You can use it for chords (useful when you start learning) or just tune your guitar strings. You can also tune bass, which is a nice extra (didn't use it for that, as I don't own a bass yet). The screen turns green when you hit the perfect pitch, which is a nice visual clue.

Be aware that this tuner must be clipped to the guitar in order to process sound. For an acoustic, clip it around the rosette, and for the electric, clip it to the headstock.

I know it's just common sense, but it makes so much of a difference to practice with your guitar always in tune.