Left Hand Position, using the fourth finger
You will notice that many guitar methods tell you to use your third (ring) finger for playing the third fret. I have found that you can keep your hand in a better position if you use your fourth (little) finger to play notes in the third fret, particularly on the first three strings.
This is based on ideas from Anthony Glise' book 'A Classical Guitar Pedagogy', he explains how use of the fourth finger helps keep the hand in a better position. The book can be pretty heavy going, but I would recommend it if you wish to read about technique in detail.
Use of the fourth finger also frees the third finger for playing notes on the lower strings. It is easier to keep the third finger free from the start, than to switch when you need these skills. It also helps you keep your fingers over the fret board, there is a tendency for the fingers to rest below the fret board if the third finger is used.