Air guitar is the easiest instrument to take up because everyone has one. If you've never played air guitar before, all you need is some good music to listen to and a little imagination.
Turn on some music. Be sure to choose lively songs with prominent guitar riffs.
Step2
Position your hands so that your strumming hand is over your belly and your other hand is extended away from your body. This other hand is simulating holding the neck of the guitar, so your palm should be turned up and your fingers and thumb curled up.
Step3
Strum by moving your strumming hand up and down. Keep your palm toward your belly and your fingers loose. You can also hold an imaginary guitar pick in your fingers if you'd like.
Step4
Move your fingers on your neck-holding hand like you are playing chords. Listen to the chord changes in the music and reposition your fingers with each chord change. Move your hand up and down the imaginary neck as you play higher chords.
Step5
Get into your performance by nodding your head up and down and moving your feet once you have mastered the strumming and chord-playing.
Tips & Warnings
Make sure you keep a rhythm with your strumming hand and don't just flail it around. Try to match the strumming pattern in the music.
Make well-defined movements with your fingers on the neck-holding hand. If you were playing a real guitar, you'd be pressing down on the strings to play chords, so resist the urge to do loose finger movements with that hand.
Practice in front of a mirror to monitor and perfect your technique.