Different styles of playing demand different types of strings; but, unless you are a specialist in a particular style, your guitar came with strings that will normally give the best results. You may want to make your guitar easier to play and use one of our lighter string sets, but your bridge saddle and neck may have to be adjusted to prevent fret buzz. A classical guitar has much lighter bracing than the usual steel-string acoustic guitar, and using steel strings on it will literally pull it apart.
Strings don’t last forever. As you play your guitar, you will notice its sound will gradually lose brilliance. It will begin to sound slightly muffled because the strings have begun to wear out. Human skin moisture causes strings to become dirty and this eventually deadens the sound of the strings. At this point, the entire set should be replaced. Replacing only one string causes an unbalanced sound.