So here you are, you got a new guitar and you want to learn. However before you can learn, here is some basics the average guitarist should know:
1) At Home
When at home, in between guitar lessons you still want to learn, so go on to the internet and search for sites like this or go on YouTube and look for guitar tutorials. There is some vital information on these sites and you can also learn new songs as well.
Now that you've been given something to learn, LEARN IT, don't just muck about when you don't know what to do, pick up that guitar and practice but don't go from one extreme to the other, for example, playing the same song over and over again, you will never improve this way.
When learning a new song, always go for something which is just out of your reach, doing this can help you improve your techniques.
2) At The Music Shop
You're at the music shop, and it's time to get a new axe (=guitar), when you're testing a new guitar DON'T play: "Smoke On The Water", "Come As You Are" and "Stairway To Heaven". Also DON'T do slides on the neck and if your using a guitar with a wobble bar, don't do dive bombs all the time. These will just annoy the shop keeper and the people around you.
DO look for any nicks and scratches on the guitar and test all the pickups. Look at the neck, is the action to high? Or is it to low? Has the truss rod been modified?
All of these are the things you want to consider when buying a new guitar.
Also, buy the guitar which is most suited to you style. Ex: There is no point in buying a semi acoustic, 1 small single coil pickup guitar if you want to play metal.
3) Improve Your Playing Techniques
When playing there are a few things you should do.
A lot of new guitarists play with their thumb over the top of the neck and their fingers at an angle, doing downstrokes only and looking at their right hand from time to time because they have to look where the correct string is.
All of these things are wrong.
Play correctly, try and prevent your thumb from going over the top of the neck, keep your hand at around about a 90 degree angle to the neck, pick up and down, not just down as this will help you play faster and keep you hand anchored to the pick guard, this will help you pick the right strings without looking at your right hand.
These are all the things you should know as a new guitarist. Do these things and rock on!