How often should I change my strings?
Guitar strings age in several ways - they stretch, tarnish and get contaminated with sweat and dirt. Professional players change strings before each gig. For general light home use we would recommend you change your strings every 6 months as a minimum. If you play a lot then every few weeks would be more appropriate.
Wiping your guitar strings with a clean cloth after EVERY use will help to make your strings sound bright for longer, but however meticulous you are you cannot prevent the gratual stretching of your strings which will effect intonation, sustain and tone.
For longer-lasting strings consider coated strings - you can expect them to last maybe twice as long as comparable uncoated strings, but not much more than that.
Changing strings can seem like a chore, but you will always be rewarded with a brighter, fresher cleaner sound from your guitar - whether it is electric, acoustic or classical.