Buying Good Guitar Strings are very Important

Guitars are only useful if they have strings. Though strings look rather insignificant in size, they have a profound effect on your playing experience. Here's a point to note: A lot of amateur guitarists don't buy guitar strings until they cut one of their strings.
That's not correct because your guitar strings get degraded with use. This is specially true of metal strings. These are prone to rust and corrosion. So, depending on the level of sound quality you desire and how often you use your guitar, change your strings often.
Now into the main thing (How to buy guitar strings)...
There are different types of guitar strings and the type that you should go for depends largely on your type of guitar (Is it an electric guitar, acoustic guitar, etc), the kind of music you want to play, your volume requirements (not really an issue unless you play unamplifed acoustic), the tone contrast you prefer,the level of your play and how much you are willing to spend among other things.
There are nickel, nickel-plated, stainless steel and nylon strings. The most common type are nickel-plated guitar strings. Their sound is brighter than those of pure nickel strings but not as bright as stainless strings.
Stainless steel strings are resistant to corrosion but have a rougher feel when compared with nickel-plated strings. Furthermore, they have very good sustain. That means that those are the ones you need if you want strings that will help you hold those notes for as long as possible.
You have a lot of choices to make from type to brand. There are so many brands to choose from. You can go for popular names (those usually come at a higher price) or you can just go for anything that gives you good sound.
Guitar strings also come at different prices. For as little as $5 you'll get a pack of strings. However, you can spend as much $40 when you want to buy guitar strings. It all depends on what you want. Just keep in mind that you have to replace your strings regularly for the best sounds.