First, shutdown your PC and remove the mains plug, unplug the keyboard (remember which socket) and hold it upside down to release any debris from inbetween the keys (pressing the keys is a good way to release it).
If you have a can of compressed air then use it to blow any debris from around and under the keys, if not then use the hose of a vacuum cleaner to remove it.
Now take one of the cotton buds and put a couple of drops of the cleaning fluid on it, use the cotton bud to clean the sides of the keys.
After cleaning the sides of the keys take your lint free cloth and dampen it with your cleaning fluid (don’t put the liquid directly on the keyboard), give the surface of the keyboard a good wipe over using the cloth to trace the contours of the keys.
When you have finished give the keyboard a wipe over with the dry cloth/duster, you should now have a nice clean keyboard, to clean it more thoroughly follow the guide below.