Guitarists can never have too many guitar strings. And while some people think you only need to change your strings when one breaks, many pro players actually replace their strings every couple of weeks — or even before every show! New strings sound sweeter, feel nicer to player, stay in tune better, and simply bring your guitar to life.
The only thing you may need to get right, though, is the string gauge and type. Every guitar is specifically set up for a certain gauge (the string thickness), and if this is changed without a proper setup then it can affect the playability of the guitar. The majority of electric guitars come with 9-42 or 10-46 strings as standard, so these are a pretty safe bet.
You'll also need to make sure you get electric guitar strings if they have an electric guitar, and acoustic guitar strings if they have an acoustic. We know it sounds obvious, but buying the correct strings for the instrument is crucial for it to sound and perform properly. Guitarists generally have a favourite string brand too, so you might need to sneakily find this info from the person you’re buying for.