Stringing Your Guitar Properly - Since every guitar is a little different, and some take strings differently than others, I can't get too deep into the basics here. Take a look at your strings that are on now, and install the new ones in the same manner for the most part. Some take strings through the back of the guitar body, and some just thread through the tailbar or tremolo. What I will get into in this lesson is the correct way to wrap the strings around the tuning post, as this can have quite an effect on how well your guitar operates and keeps its tune.
First you will want to make sure that you wrap the string around the tuning post in the proper direction. You will know the proper direction because the string should go from the nut to the closest side of the tuning post. Look at your guitar and you will notice that after the strings go through the nut at the end of your fretboard they change direction slightly to go to the proper tuning post. Never make the strings change direction even further by going to the wrong side of the tuning post. This will cause unnecessary stress on the strings and your nut, as well as other problems in the future.
Once you are certain which side of the tuning post your string should go to, you can start thinking about how to wrap it properly. There is a trick we use to help lock the string in place at the tuning post so it doesn't slip around the post and fall out of tune. The idea is to sandwich the string where it passes through the tuning post between two of the wraps of string around the post. If you look closely, you'll see that tuning posts have an hourglass shape to them, causing the strings to want to stay wrapped around the middle of the post instead of higher or lower. This is a good thing and can be used to our advantage to lock your string in place and help keep it from slipping out of tune.
To accomplish this, you'll want to put the string through the hole in the post as you normally would. You'll learm from experience how much slack you should leave in the string, you'll want enough to make 3 to 4 wraps around the post. Not enough wraps and your string may slip, too many and it will have too much room to stretch and settle, also causing the guitar to fall out of tune.
When you start to turn the tuning post to tighten the string, you'll want to stop as the backside of the string sticking out of the post comes around. You want to take this loose end and push it under the guitar string the first time. This means that your string will go over the top of the part sticking out and that hourglass shape will cause it to put downward pressure on the top side of the string thats sticking out. Keep your wrap on top of the string where it goes into the hole on the other side as well as you wind the string. Once you get a full turn on it and the sticking out part comes around again, bend it upwards sharply both to kink it where it exits the post and to now force the rest of the wraps around the lower side of the post. Doing this with that hourglass shape will cause the new wraps to push upwards on the string where it goes through the post and should effectively lock it in place.
You will notice that the string is now tightly wrapped around both sides of where the string-end goes through the post, and add that to the kink where the string exits the hole and you have a string thats pretty well locked in place and should not slip out of tune. It is important to always keep the string tight as you turn the tuning post so there isn't any slack in the wraps that can tighten and cause you to fall out of tune.
Well, thats pretty much it for installing strings on your guitar in a manner that will help it to keep its tune without using those string-lock things.