Apart from having a lot of willpower here are some tips and ideas which you should keep in mind:
# Use all FOUR fingers of your Left Hand. Go through one of my early blogs about technique and fingering, it will help you to get a focus on what I mean. We have four fingers available for our fretting hand, which is usually your left hand (if you are a lefty think in mirror version!!). Use them all, the sooner you will do this, the better your playing will get. Usually people leave out the use of the pink. Why? Because it is the weakest finger of the four, work on it seperately with individual exercises which will train you to use your pink.
# Posture = How you sit [or stand up] while holding the guitar: Try to sit straight, no sofas please, use a hard chair which can support your back. May feel a little boring at first, but it will help you to concentrate. Where are those teachers of the past we used to have in primary school who told you off for not sitting straight in your chair? There is a reason for anything in this world, sitting [or standing] upright is one of them as it helps to maintain you concentrated on what you are doing. If you use a guitarstrap (which is what I do, even when I sit down!!) have it as high as when you would sit and play the guitar. Does not look cool? Maybe you should concentrate more on your haircut and doing guitaraccrobatics in front of the mirror or an audience in your livingroom! Forget the joking and look at people who can play the guitar well, how do they hold the guitar? Yes there are a few exceptions, but most of them will not have their guitar slung that low so it will reach the point of their shoes. Once you have learned how to play you can experiment with your posture and how low you can hold your axe, you may even want to try sliding on your knees while playing through some of your favourite licks, or playing with your teeth (Nickel strings taste really rusty and metallic!, but some of your may like it as desert!) If you get bored with any of the above why not play some riffs behind your back, this will really show you and your audience how well you can play. No seriously, I am not kidding, this is a good trick to try, but it may not feel so comfortable after a while. If you practise like this regularly you may be able to beat that other kid in your class!
# Thumb: Find a neutral postion, which is at the back of the guitar, opposite your first finger. This is a neutral postion, from there the thumb can move anywhere, and yes, at times it will even come over the neck. But for now keep it at the back since you are not involved in stringbending yet!!
# Wrist: Keep it flexible, try to move it around as you are holding some of the basic chords like G and Em, make sure that the open strings will sound, that your fingers do not muffle the strings, if they do, move your wrist, keep thumb at the back and see if you can get that chord to ring like a bell!!
# Listen to your playing: Sounds all too obvious? It is quite common for people to concentrate on the motorskills in the beginning, they may forget what they are playing, as they are busy watching their fingers, and often looking at sheetmusic as well. It helps if you can memorise what you are playing as this will make it easier to concentrate on listening. This advise also goes for Intermediate and Advanced players, memorising any song will help you to play it better.
# Enjoy what you can play, do not think too much about the future and what you COULD play. This goes especially for people who start out a little later in life. Usually children will enjoy what they can do and muck about with it a bit, which is great as you need to experiment to push your playing to the next level. It is all about being in the moment, enjoy what goes on, do it as well as you can for now and carry on with it!!
Stay upright and tuned!!