Replacing guitar strings can brighten up your music and give you a new passion for playing your guitar. However, it can also be intimidating to a new guitarist. This is even more true for someone whose first guitar cost many hundreds of dollars. There is a sight possibility of damaging your instrument while changing guitar strings, but armed with this information you should have nothing to fear.
Choose the Right Strings
You need to start with the right strings. There are many types of guitars and each one has strings that are specific to them. For example, if you put steel strings on a classical style guitar you will risk warping the neck or pulling the bridge off the guitar. Make sure you buy classical guitar strings. These are made specifically for classical guitars, also known as nylon string guitars.
Beyond choosing the right type of strings you will have a choice of string brands and hardness. Hard strings will sound brighter and intonate longer, but they will be harder to fret. A softer set of strings will be easier to play for a beginner but won't sound as crisp. You will also find that they will probably go dead more quickly. Unlike a steel string guitar where the strings can last much longer, a classical guitar will sound better with regular string replacement. To know whether you prefer the sound of softer or harder strings will be a matter of trial and error.
How often you should replace your guitar strings is mostly up to you. It depends on how much you play and how much you want, or need, that crisp bright sound that new strings can provide. When I was practicing several hours a day I would change my strings every month or two. But now that I play casually I only replace them when they sound really dull or I just get tired of them and want something to motivate me to play. New strings can be very inspirational.
Replace One String at a Time
For a beginner I suggest that you start with replacing one string at a time. This lets you see how the string comes off and goes back on. You will also have the other strings near it as a guide. Which string should go first? I recommend starting with string #1, or the high E-string which is the smallest string. This is the one at the bottom when holding the guitar as if you were playing it.
Loosen the tuning machine on the string noting which way you have to turn it. Hold the guitar like you would if you were playing it and unwind the string by turning the machine clockwise, or to the right. This is the opposite direction from normally unscrewing something. If the person before you wound the string wrong (which is possible) then you will need to turn the tuning machine the other direction. Continue to turn the machine until the string is either all the way undone, or loose enough that you can easily pull it off.
Note how the string is tied at the bridge of the guitar and then undo that end as well.
Grab the smallest string from your pack of new strings. Notice that this string is usually identical on both ends. You will want to reinsert the new string starting at the bridge. I find it easier on my guitar to feed the string from the sound hole side of the bridge pushing it towards the bottom of the guitar. Your guitar may be different depending on how it is constructed. Find what works for you.
After tying the new string to the tie block you need to attach the top of the string to the tuning peg. String #1 should wind so that the bulk of the excess string winds out towards the side of the guitar. This allows plenty of room for the next two strings to pass over string #1 without touching the excess. When you put the new string on you will turn the tuning machine counter clockwise, or to the left. This will wind the string over the top of the tuning peg. You will have lots of extra string. Be sure to pull the string fairly tight to get started since the string will stretch considerably. This assures that you don't have too much string wound around the tuning peg.
Strings 1, 2 and 3 work exactly the same way with one exception. String #3 will still wind over the top of the tuning peg while turning the machine to the left, but you want the excess to wrap towards the inside of the guitar on the tuning peg.
Strings 4, 5 and 6
Continue up the guitar with strings 4, 5 and 6 in order. You will notice that the tuning machines turn the same direction in your fingers, but the pegs actually turn the opposite way. When you pull string #4 out of your replacement set of guitar stings you will notice that the two ends are different from one another. One end will be more loosely wound with wire than the other end. The loosely wound end is the one you tie to the tie block at the bridge. Again, observe how the old string came off and how the strings around it are tied.
Sometimes I have had problems getting strings 4-6 into the bridge. Be patient and you will find the best way to thread them. While it is generally easier to feed the string from the sound hole side of the bridge down towards the bottom of the guitar, with the 4-6 strings being more loosely wound at the tying end I have sometimes had trouble getting them through the bridge. This depends on the replacement guitar strings that you have. If end up feeding the string from the bottom of the guitar up towards the sound hole you may need to use a pointed object to help pick the string up and over the bridge.
String #4 should wind over the tuning peg and towards the inside of the guitar. Strings #5 and #6 will wind over the peg and toward the outside of the guitar. Actually strings #2 and #5 can go either direction. See how they are currently wound and follow that pattern if you aren't having any problems with the guitar now.
Once you get all 6 strings on the guitar you will find that you have a lot of excess string. You can deal with this in a couple of ways. I do not recommend you leave the excess string hanging out. Some people apparently find this "cool," but it looks sloppy and can be dangerous. One of the strings can easily poke someone in the eye.
You can trim the excess string with a pair of fingernail clippers. Be aware that trimming the metal wound strings can damage the clippers so that they won't trim nails well after cutting the guitar strings. Don't use your mom's, or wife's, favorite clippers for this job or you could be playing your guitar in the doghouse.
There is also a way to roll the string into a small coil and then feed the end of the replacement string through the coil several times so that it will hold itself in place. You may want to do this if you have a fear of breaking a string and want the excess to use in case it breaks in such a way that you can re-tie it. I have tied my guitar strings like this before, but have never broken a string to need to re-thread it. Nylon strings don't break as easily, nor nearly as often as steel guitar strings. I would not worry about saving the extra length of string.
My recommendation is to trim off the excess.
Tune and Enjoy
At this point you will have a lot of tuning to do. New strings will stretch quite a bit. By the time you get all 6 strings tuned it will be time to start again. But after several minutes the strings will be stretched enough to hold their tune through a song or two. It is extra work to keep tuning them, but fresh strings sound so much better.
I hope this gives you the confidence you need to change your own guitar strings. You will have to try many different strings to find your favorite kind. While I am sure there are better strings available I have a brand and model that I consistently go back to when I don't want to venture out into anything new. They are the Augustine Blue Label Classical Guitar Strings. Try several different brands and models of guitar strings until you find the ones you like.
If you have any questions please leave a comment and I will help you as much as I can. When you get the feel for the basics, read about more advanced classical guitar string replacement for ways to give your guitar a good cleaning and better string life.