Just a quick addition here since no one seemed to answer the stretching with cartridge razor question. The better cartridge razors do indeed accomplish some of the stretching for you. They have that little rubber strip that grips and pulls the skin on your face to stretch it a bit...it doesn't take much to help. Also the multi blade cartridges tend to do this even more as they dull, since the first blade will grab and tug, then the next sharper blade will do the cutting.

So you DO need to make sure you are stretching the skin if you want the closest shave!