What you need:
>Flathead screwdriver (I am using one off my multitool
>Lens cleaner (glasses cleaner)
1)Unplug from computer
2)Place flathead screwdriver under the key and push downwards, covering key with other hand (Otherwise they fly off!)
3)Place key on clean desk
4)Repeat steps 2 & 4 placing keys in order, as they look on the keyboard.
5)Using the toothbrush scrub around where the keys go and shake out the dirt
6)Repeat until you don't see any more dirt
7)Replace keys, cleaning all surfaces of the key,
(some have metal springs, they should just slide downwards towards bottom of keyboard, but all are different, have a look how it goes back)
8)Dampen the microfiber cloth with the lens cleaner and scrub each key
9)Wipe around keys
10)Plug in keyboard, open Notepad or TextEdit and test each key to ensure it is in the right spot.