The main thing a Beginner guitar player should concentrate is the discipline and contrik o the Guitar. Doing regukar practicing is the only way. There is no benefit if you practice 5 hours abd from the next day you would not practice for the next 4-5 days. You have to practice everyday.
Exercises For The Beginner -
1. Chromatic Finger Exercises
2. Alternating Finger Exercises
3. Chords Shifting Exercises
4. Chords Arpeggio Exercises
5. Various Strumming Exercises
These are the exercises a begginner should practice everyday to increase the proefficiency level. And most importantly these exercises should be played with a decent METRONME.