Even after that long essay I missed a few of important points.
If you flush your shifters with WD-40 you need to wash them out before relubing them. WD-40 is a solvent and you don't want solvent contaminating your new lube.
If you take the front cover, namplate, off be very careful putting it back on. The small tab that sticks through the main lever can get bent very easily. If you push the tab in too far you may lose or hinder your shifting to the last one or two large cogs on your cassette. To fix the problem, you have to take the shifter apart and bend it back out.
One last point that I have never seen discussed before. If you are going to store your bike for any extended period of time; shift the small levers as many times as possible so your bike is in the small chainring, small cog combination. This leaves the shifters with all of the springs in their most uncompressed state and they should work better longer. I have only seen one broken because of this (not one of the four mentioned above), but hey why take chances for something that is so simple to do?