What Should I Buy In Addition to My First Guitar?
In addition to a guitar, you will likely need some accessories. The type of music you want to play will determine which accessories you should buy.
Picks
Unless you plan to play fingerstyle, you will need some picks. Picks come in a variety of materials, shapes, sizes, and thicknesses, so you should buy a few different kinds to find the one that is comfortable for you. Picks are very cheap, so a few dollars will get you quite a few. If you find a pick that you like, you may want to buy them in bulk. They are cheaper this way and you will have a lot of spares in case you lose your picks (trust me, you will).
Amp
If you are playing an electric guitar, you will eventually need an amp. However, you shouldn't skimp on the price of your first guitar just to get an amp. Electric guitars can be played without an amp, so you don't need one right away, but it is a good idea to get one as soon after buying your first guitar as possible. A pretty good practice amp can be purchased for around $100-$150.
Chromatic Tuner
Tuning the guitar without a tuner is often very difficult for beginners unless they use an electronic tuner. There are many different tuners available. Some tuners are specifically designed for a guitar in standard tuning and will usually have lights for each string to help you tune. Chromatic tuners are better since they can be used for other instruments and for alternate tunings on the guitar. You should be able to find a good chromatic tuner for as little as $20.
A Guitar Cable
If you have an amp, you will need a cable to connect your guitar to it. Guitar cables come in a variety of lengths. A ten foot cable is a good length for your first cable. It will allow you to play a reasonable distance from your amp. A decent ten foot cable will probably cost $15 or more.
Music Stand
A music stand is great for holding music while you are playing. It can be difficult to read music in a comfortable playing position without a stand. A good music stand can be purchased for around $40. There are cheaper stands, but these tend to be folding stands that are only a metal frame. These stands are often flimsy and won't hold as much as a better stand. An alternative to buying a music stand is to use the music stand on your piano or keyboard if you have one. This won't be as portable as a dedicated music stand, but it will work in a pinch.
Stool or Other Armless Chair
A chair without arms is essential for a proper playing position. You may already have something like this. If not, a stool or folding chair are fairly cheap options. The most important thing is to have something that will be comfortable to sit in for long practice sessions. If you have back problems, you should probably avoid stools and choose something with back support instead.
Metronome
A metronome is an essential tool for learning to count rhythms and how to keep a steady tempo. It provides a consistent click at a tempo you specify. This click allows you to more easily play in time. There are many varieties of metronomes. Some are very basic, giving you only a simple click. Other metronomes may give you numerous sounds and options for various time signatures and rhythms. The simpler metronomes are plenty for practicing in most cases. They also tend to be more durable.
String Winder and Wire Cutters
These two tools will make changing strings a lot easier. A string winder has a part that fits over the tuning machines on the guitar. There is a handle attached to this that you can crank to remove strings much more rapidly than doing it by hand. Most string winders also have a notch cut in the head part of the winder that can be used to remove the bridge pins from a steel string acoustic guitar. These can be difficult to remove without a special tool.
A set of wire cutters will come in handy for cutting off the excess string when you change strings. There will usually be at least a few inches of string left over after you have changed the strings.
You can probably get both of these tools for under $5 total. There are also tool sets guitars that include string winders and wire cutters along with other tools that can be used for working with your guitar. These are more expensive, but may be worth it if you want to get the other tools.
Extra Strings
You will likely break many strings as a beginner. This will often occur when you are tuning and tune the string higher than it should be tuned. Keeping extra strings on hand will allow you to quickly get back into playing. The strings that are broken most frequently are the G, B, and high E strings. Luckily, strings can be purchased individually, so it is easy to stock up with a few extras for each string. These individual strings usually cost around $1.
You should also have some complete sets of strings on hand for changing the strings on your guitar periodically. Strings degrade in sound quality and don't stay in tune as well as they age, so they should be changed regularly. A pack of good strings will set you back roughly $8 or so. However, it is possible to buy in bulk online and get the price per pack down to around $3-$5 per pack.
Guitar Stand
A guitar stand is an easy way to protect a guitar when you aren't using it. A stand will secure the guitar in an upright position and are small enough to not get in the way, yet allow quick and easy access to your instrument. Make sure to get a stand that secures the guitar in some way. Some stands don't include anything to keep the guitar from falling over. Most stands will include a U-shaped part to hold the guitar neck and something that goes across the end of the 'U' to lock the guitar in place.
Price: $15+
Full Length Mirror
A mirror will allow you to see yourself while you play. This can help you learn to play with proper technique since you will be able to see what others see when they watch you.
Music Dictionary
A music dictionary will allow you to look up unfamiliar musical terms. Most dictionaries will cover words that are used in written music, important composers and other figures in musical history, musical instruments, and other topics.
Price: $5+
Gear to Consider for the Future
The items listed below aren't essential for most players, but you may want to add some or all of them to your gear collection over time.
Capo
A capo is an easy way to transpose music into other keys without having to know music theory. If you do a lot of strumming to accompany yourself or others, you may need to transpose music into a different key.
Price: $10+
Slide
A slide fits over the fingers and is used to play slide guitar. They are usually made of metal or glass. Even if you don't intend to play a lot of slide guitar, it may be worth getting a slide. A slide is pretty cheap and is fun to experiment with. Some players even make slides from glass bottles or metal pipes.
Price: $0+
Foot Stool
Foot stools are mostly used in playing classical guitar, but they can be used if you play other styles too. They allow you to play in a better position by placing the guitar on the left leg rather than the right. The stool elevates the leg and guitar so they are at a comfortable height.
Price: $10+
Guitar Strap
A strap is used to play standing up. If you intend to perform, you will likely be standing up, so a strap is essential. Some straps include a locking system to prevent the strap from coming off the guitar.
Price: $5+