For a guitar with nylon strings, a non-dampened towel or one slightly dampened with water will suffice. For guitars with steel strings, there are guitar string cleaners that are manufactured for use like Fast-Fret String Cleaner, Dunlop Ultraglide, Dr. Stringfellow, and the like. However, you do not have to use these products if you cannot afford them. 70-90% rubbing alcohol can also be effective, as can pre-shaving gel. [3] X Research source
It is important to clean both sides of the strings just as it is important to clean both sides of your teeth. Don’t worry if the head gets lifted off its mount; even if the tuning pegs get a little messed up you can always retune your guitar. You will probably notice that your guitar strings change color a little, or that the cloth comes away with grey streaks. [4] X Research source This is a sign that your efforts are working.
If you do not have the product packaging anymore, a good rule of thumb to follow is to consider the kind of guitar you have and the genres it’s made to play. Acoustic and flamenco guitars that focus on classical and folk music usually possess nylon strings; electric and bass guitars associated with blues, country, and rock and pop music are more likely to have steel strings. [7] X Research source
Dunlop Lemon Oil, Tone Finger-Ease String Lubricant, or GHS Fast Fret are all commercial oiling products you can buy that are made specifically for guitars. If you need something cheap and readily available, you can try olive oil, baby oil, or Vaseline. [9] X Research source You never want to apply the lubricant directly to the strings as there is a good chance you’ll get excess grease on the fretboard which will be difficult to clean up.