TL;DR
Almost all guitar cleaning is a dry microfiber cloth, and the finish on your instrument decides everything you may do beyond that. Wipe the strings and the body after every session, use products made for guitars rather than household cleaners, and never put a household polish or a solvent anywhere near a finish you have not identified.
Identify the finish before you touch anything
A guitar's finish is a thin layer of one of several very different materials, and the wrong product ruins it.
Gloss polyurethane or polyester is the finish on most modern instruments. It is hard, glossy, and durable, and it tolerates guitar polish well.
Nitrocellulose lacquer is thinner and softer, used on many vintage and traditional instruments. It reacts badly to a lot of things, including some plastics and rubber, and it can be dulled by products meant for polyurethane.
Satin or matte finishes must never be polished. Polish fills the microscopic texture that creates the matte look and leaves shiny patches that cannot be undone.
Oil-finished and unfinished wood needs a completely different approach, usually a specific oil rather than a polish.
If you do not know which you have, look the model up or ask a repair shop. When in doubt, a dry microfiber cloth is safe on all of them.
How do you clean a guitar body?
Wipe it with a dry microfiber cloth after every session to remove fingerprints and skin oil. For a gloss finish, a guitar polish applied to the cloth rather than the instrument removes what dry wiping cannot. Never apply household furniture polish, cleaners containing silicone, or solvents.
What never goes on a guitar
Household furniture polish. Many contain silicone, which soaks into the finish and makes future refinishing or repair difficult or impossible. A repair shop will tell you this is one of their least favorite discoveries.
Ammonia-based glass cleaner. It attacks lacquer.
Alcohol. It dissolves nitrocellulose lacquer on contact and can haze other finishes.
Any solvent. Acetone, paint thinner, and similar products remove finish.
Water on the fretboard. An unfinished rosewood or ebony board absorbs water and can swell, and water sitting at a fret edge can lift it.
Paper towels. More abrasive than they seem, and they can leave fine scratches in a gloss finish over time.
Use products actually sold for guitars. They are inexpensive and formulated for exactly these materials.
The routine after every session
Wipe the strings first. A dry cloth run along the top and, more importantly, under the strings between them and the fretboard. Skin oil and sweat on strings is what corrodes them.
Wipe the body, the back of the neck, and the headstock. Dry microfiber.
Wipe the hardware: bridge, tuners, and pickups on an electric. Sweat corrodes plated hardware, and the bridge is the spot that suffers most.
That is it, and it takes under a minute. Doing it consistently doubles or triples string life.
Why do my guitar strings go dead so fast?
Skin oil, sweat, and dead skin work into the string windings and damp their vibration, and corrosion follows. Wiping the strings top and bottom after every session is the single most effective fix. Washing your hands before playing helps, and coated strings last longer for players with acidic sweat.
The fretboard, which depends on the wood
Unfinished rosewood, ebony, or pau ferro boards get dry over time and can develop cracks at the fret slots.
Clean them when you change strings, which is the only time the board is fully accessible. Wipe out the grime along the fret edges with a dry cloth or a soft brush. For heavy buildup, a fretboard-specific cleaner, applied sparingly on a cloth.
Condition sparingly, two or three times a year at most, using a fretboard conditioning oil made for instruments. A drop on a cloth, worked in, then the excess wiped off completely. Over-oiling is a real problem: it softens the wood and can seep into the neck joint.
Maple boards with a finish on them need none of that. They are cleaned like the rest of a finished body, with a dry cloth. Never oil a finished maple board.
Do not use household oils. Cooking oil goes rancid, and furniture products often contain silicone.
Cleaning frets
Tarnished frets can be polished with a fret polishing cloth or very fine steel-substitute pads, with the fretboard masked to protect it.
Steel wool is the traditional method and carries a real risk on an electric guitar, since the fine particles are magnetic and stick to the pickups permanently. If you use an abrasive pad, use a non-shedding synthetic one, and cover the pickups either way.
This is a string-change job. Do not attempt it with strings on.
Acoustic guitars specifically
Wipe the top, which takes the most contact and the most sweat.
Clean the area around the soundhole and under the strings gently, since dust collects there.
Do not put anything liquid inside the body. There is no way to get it out.
Humidity matters more than cleanliness for an acoustic. Very dry indoor air in winter can crack a top or lift a bridge. A case humidifier and a hygrometer are worth more than any cleaning product, and a wet Oregon winter means the reverse problem in some homes, where too much humidity swells the top.
Source: Guitar manufacturer care and maintenance documentation
Storage and the case
Keep a guitar in its case or on a proper stand, not leaning against a wall or a radiator.
Watch what touches the finish. Some rubber, foam, and vinyl react with nitrocellulose lacquer over time and leave permanent marks, and that includes some guitar stands and straps. Look for stands specifically labeled as safe for lacquer finishes.
Vacuum out the case occasionally. Grit in a case ends up against the finish.
Keep instruments out of a hot car and away from direct sun and heat vents, the same rule that governs most delicate gear in our guide to cleaning tools and equipment around the house and the instruments in how to clean drum heads and hardware.
When to hand it to a technician
Finish damage, cracks, lifting bridges, and fret work are repair jobs.
A guitar with a genuinely filthy fretboard, corroded hardware, and unknown history is worth a professional setup, which will include a proper clean.
Vintage instruments should be cleaned conservatively. Original finish is part of their value, and aggressive polishing reduces it. The same conservatism applies to old piano keys, discussed in how to clean piano keys without water.
FAQ
Can you use furniture polish on a guitar?
No. Many household furniture polishes contain silicone, which soaks into the finish and makes future repair or refinishing difficult or impossible. Repair technicians consider it one of the worst things to find on an instrument. Use a polish sold specifically for guitars, applied to the cloth rather than the guitar.
How do you clean a guitar fretboard?
On an unfinished rosewood or ebony board, wipe the grime out with a dry cloth or soft brush at a string change, using a fretboard-specific cleaner sparingly for heavy buildup. Condition two or three times a year at most with an instrument fretboard oil. Never oil a finished maple board.
How do you make guitar strings last longer?
Wash your hands before playing and wipe the strings after every session, running the cloth both on top and underneath between the strings and the fretboard. Skin oil and sweat work into the windings and dull the tone. Coated strings help players whose sweat corrodes strings quickly.
Can you use alcohol to clean guitar strings?
It is risky. Alcohol dissolves nitrocellulose lacquer on contact, so any drip onto the body or neck can cause permanent damage, and it can dry out an unfinished fretboard. A dry cloth after every session does most of the work, and string cleaner products made for guitars are safer.
Should you use steel wool on guitar frets?
Not on an electric guitar. Steel wool sheds fine magnetic particles that stick permanently to the pickups. Use a non-shedding synthetic polishing pad or a fret polishing cloth instead, with the fretboard masked and the pickups covered, and only during a string change.
How do you clean a guitar with a satin finish?
Dry microfiber cloth only. Never use polish on a satin or matte finish, because polish fills the microscopic surface texture that creates the matte look and leaves permanent shiny patches. If a satin finish needs more than a dry wipe, ask a repair shop what is safe for that specific instrument.
Instruments live in rooms that need looking after too. If keeping up with the rest of the house is the harder job, get a quote or read more about house cleaning services.