There are many different brands of guitar cleaning and polishing liquids, creams, and sprays but what the manufacturers do not usually disclose is that:
1. If you keep your guitar in good condition then all you usually have to do is simply wipe it down with a cloth after each practice or performance session.
2. Different types of guitar finish can react to cleaning and polishing formulations and so you need to be know something about this.
3. If you use a furniture polish that contains silicone, you will get a great shine but any future repairs to dents and scratches will be problematic.
A quick wipe down with a micro cloth or soft cleaning cloth is usually enough to keep a well finished guitar looking good. The strings will also need to be wiped down to remove accumulated dirt, oil and skin cells as these will affect both the tone and the life-span of the strings.
It is a good idea to polish your guitar occasionally because the Carnauba wax in the polish will form a thin protective sheen and will usually add to the lustre of the guitar finish. However, take note of the fact that guitars finished with Nitrocellulose can react with some types of polish resulting in a cloudy appearance that is hard to remove. If you are going to use a polish, then ensure that it has been tested on your type of guitar finish. I use Musicnomad Guitar One for polishing and Detailer after practices because my skin is very acidy and my guitar is finished with Nitrocellulose which reacts chemically to acid sweat. Also take note of the fact that if your guitar has a satin (semi-gloss) or matt finish, then regular polishing will eventually change the finish from mat to semi-gloss and from satin to gloss.
The cheapest way to clean and polish your guitar is by using a household spray-on furniture polish. This results in a high gloss effect because of the silicone contained in the product. The drawback is that if you have to repair or refinish the guitar because of dings and scratches and so on, then whoever does the job will have a hard time removing the silicone before he can apply either a lacquer or a varnish finish. The silicone penetrates most finishes and prevents any new application of lacquer or varnish from adhering properly.
Fret board maintenance
There are a number of products on the market for cleaning fret boards. Most, if not all of them contain Lemon Oil, which is really all you need. When you change strings then use a little Lemon Oil on a rag, rub down the spaces between each fret and then dry it off with a clean cloth. This will keep the fretboard clean and sufficiently oiled.
Here again there are products on the market that come in handy applicators but all you really need to do is to wipe the strings down with a damp cloth from time to time. Run the cloth both over and under the strings and then use a clean cloth to repeat the process. The easiest way to do this to use a thin cloth which you slip under the strings and then fold back over them. If you want to make the strings feel more slippery and less squeaky then mix up a 50/50 solution of alcohol and baby oil and use this instead of water.
Use whatever guitar polish you have to shine up the metal. Use Petroleum Jelly (Vaseline) applied in small quantities to the gears using an ear-bud to keep the mechanism moving freely.
All you need to do to prevent friction from impeding the movement of strings through the nut slots is a graphite pencil. When you change the strings, rub the tip of the pencil into each nut slot to deposit a thin coating of Graphite.