Yuck your keyboard is dirty! Nasty dirty. Maybe you've gone a little too long without cleaning it and found that some of the keys are starting to stick. Cleaning your keyboard can be done in a jiff, or it can take a good hour; It really depends on your keyboards level of "disgusting".
I've set out a step by step routine; you can carry out the first 3 steps to maintain keyboard cleanliness or just to spiff it up. Otherwise you can go all the way.
1. Blow out the crud with compressed air
Compressed air cans are super fun and actually useful for times like these. Get it right in-between the keys and pull the tighter. Blow it through every line of keys up and down. Ya! That dust doesn't stand a chance.
2. Use a Vacuum and Suck out the Debris
Put on that duster brush attachment, and run the vacuum over the keyboard keys picking up whatever was left behind from the prior shake and blow.
3. Wipe down with Alcohol
With cotton cloth and some 90% Isopropyl (ensure it's not Ethanol based) dap some of the stuff on the cloth and wipe down the keys and the surrounding surface. Get around the edges and see how well you can do getting in-between the keys.
4. Getting between the keys
An old tooth brush work well for this. Pour isopropyl into a bowl and dab the tooth brush. Brush in-between the keys getting the gunk, frequently refreshing the brush in the bowl of Isopropyl.
5. Going deep; under the keys
Getting real clean inside in out will take a bit of patience. You're going to be removing keys, but before you do make a key reference for yourself so you know how the keys go back on. I recommend using a digital camera or even running it over a copy machine.
Using a flat head screw driver or a butter knife also works great, to pry and pop the keys off one by one.
With the bottom of the keyboard exposed, give the contours of good brushing of isopropyl with the tooth brush. If you need to get into some awkward corners, a cue-tip works well. Now pad dry and pick up the loosed gunk (from the brushing) with a dry cloth.
Using your reference photo of the keyboard, replace the keys gently but firm. With each placed key, give it a few taps and make sure it moves freely.
Your keyboard is now reassembled and super clean!