Over a long period of use, keyboards can become dirty in various ways. Luckily, there is a preferred way to clean mechanical keyboards. Let's get started.
First, start by pulling the keyboard caps. You can do this will a cap puller like below or with your fingers, whichever is your preferred method. Whichever you choose, make sure you pull the cap straight up to avoid breaking the switch stem below.
Once the caps are pulled off the plungers use a can of compressed air to blow out any larger debris. There is no preferred amount of space between the tube and the keyboard. It is recommended that you keep the can as upright as possible to avoid the compression fluid from coming out. If it does, just stop and wait for it to dry out before continuing.
Now that the larger debris is removed, you can move on to the dust and grime. Use a lightly dampened microfiber towel and wipe the dusty areas clean. If the keyboard needs a more thorough cleaning you may need to go over the affected area a few times. Be sure to only make the cloth lightly damp so that water doesn't get into the plungers.
Moving on to the keys. The keys can be cleaned with warm soapy water and letting them soak. You can use a soft bristle toothbrush again to scrub any tough grime away but usually just wiping them down after the soak is enough.
Once you are done cleaning your keys make sure they are fully dry before putting them back onto the keyboard. The process can be tedious but should be done every so often to maintain your hardware. All clean!