1. Tap out the dirt.
Turn off your PC and unplug the keyboard. Put a large piece of old newspaper on a table, turn the keyboard over, and holding it a few inches above the paper, shake out any loose debris.
2. Blow out the dirt.
This step is best done outside. Use a can of compressed air to loosen and remove dirt by directing the air stream between the keys. Then invert and shake out the keyboard again.
3. Clean the key surfaces.
To remove finger oils and other dirt from the surface of the keys, make a diluted solution of standard liquid dishwashing detergent. (Do not use any harsh cleaning solutions.) Use a damp (not wet) lint-free cloth to gently clean off the key surfaces. If they're not particularly dirty, plain warm water will do. Then wipe the keys with a dry cloth.
4. Vacuum the leftover dirt.
To remove loose dirt that the other steps missed, use the dusting brush on any standard vacuum.