It is essential that correct playing position is used when playing the guitar. The basics of guitar technique include seating, holding the instrument and the correct position of both hands.
Sit towards the front edge of a chair with your left leg raised. An adjustable guitar footstool is recommended which can be purchased at most music stores. Experiment with the height of the footstool and the height of the chair until you reach a seating position you feel comfortable with.
The guitar is secured at four points of the body. The left and right thighs, the forearm and the chest. The guitar should rest flat on your left thigh and not lean backwards. Angle the guitar slightly upwards as shown in the photo.
The right forearm is positioned over the body of the guitar so that the right hand is in position to pluck the strings. The elbow should not extend out to the front of the guitar. The angle of the right hand is such that the knuckles should virtually be in line with the direction of the strings.
If your seating position is comfortable and you are securing the guitar correctly then your left arm will easily reach the first four frets of the guitar. Your left arm should not be close to your body nor be pushing away from your body. It should be able to move freely up and down the entire fretboard.