Another good hint is if you don't have that contraption (bar with base in black) they use in the video's, just move the shifter holders to the end of the bars and mount the shifter there pointing down for the last part where you reassemble the final spring etc.
That will make it super easy, doing it in your hands tends to fudge things up unless you have three hands
I just refurbished my 10 speed shifters, they now feel like new again, the new hoods make them look and smell new as well.
Almost forgot, remove/install the brake lever pins in your hand, don't bang them on some hard surface, you'll end up dinging/scratching something. You do need a punch thin and long enough to get it out as well.