1. Arrange the pillows across the headboard.
2. Get back in bed. (really)
3. Sitting up, pull the sheets up to your chest, and fold them over.
4. Slip out of the bed like a will-o-the-wisp, trying not to disturb things too much.
5. Standing next to the bed, quickly smooth the sheets.
6. Shake the duvet out, and fold it at the foot of the bed. Done.
Duvet covers are a pain in the ass to get back on after laundering them. Here's how to do it. It's like magic.
1. Turn the duvet cover inside out.
2. Reach in the opening with both arms and get your hands in the far corners -- the short end opposite you.
3. Using your hands through the duvet cover, grab the short end corners of the duvet itself, and begin pulling the duvet into the cover, gradually turning the duvet cover from inside out to outside in.
4. When the duvet is covered -- it will be a little disheveled -- spin the duvet around and grab the bottom (short end.) Holding both the duvet and the edges of the now right-side-out duvet cover, give it a shake. It should be perfect. The only way this can go wrong is if your duvet cover wasn't inside out when you started, or you grabbed the long rather than short end of the duvet.
I found that picture here: http://chezlarsson.typepad.com/myblog/2009/01/how-to-put-on-a-duvet-cover.html which has a far more detailed explanation of the process and some strong indications of a couple with an obsessive compulsive disorder about ironing polo shirts (do people iron them?). I learned this tip not here, but from Robert Verdi, the designer who used to have a decorating show with a short blonde gardener. Wouldn't you do anything this guy told you? Look: