Do you have a nylon or steel-stringed guitar? Do you generally play hard with a thick pick or soft with your fingers? The type/gauge of strings depends on your actual type of guitar, playing style, and personal preferences. -If you play hard with a thick pick then you should definitely go for heavy strings. -If you mostly finger-pick and play softly then I would go with lights but be aware if you play hard with a pick lights are easy to pop. I like mediums because they seem to be able to do both ends of the spectrum well (light finger picking and heavy strumming).