Gently pry the key off from one side. Do NOT keep prying if you hear or feel any stress on the key or board! If you can, carefully look under the board and see what you are doing. Keyboards differ from maker to maker, but most laptop keyboards I have seen use an X leg design on the bottom. Two |__| shaped pieces are on the top and bottom of every key contact, and they criss-cross, thus the X shape on the sides of the key. Under the key itself are tiny hooks and rings that hold onto the legs. The trick to taking them off is to not snap the little rings, so be careful of that. When you take the key off, this will all be easier to see.
Once the key is off, gently wash the contact point and surrounding area with rubbing alcohol and a swab. Be careful not to disconnect the rubber piece from the sensitive board underneath.
The biggest challenge is putting the key back on. You have to match the rings to the feet from one of the |__| pieces. Once you do that, all you have to do is push straight down on the key with your finger so it snaps into the hooks.