to add one more thing, if you have not read "On Writing", do so.
It certainly isn't the end-all and be-all of writing books, but the section on description and the rabbit with the "8" on its side is excellent. The short version is he writes a couple paragraphs saying there is a table int eh middle of the room, and on that table is a cage, and in that age is a white rabbit with an "8" tattooed on its side.
Never says if it is a dinner table or surgical table or granite butcher block, never says if the cage is a glass aquarium, wire cage, etc., but he does describe the "8". Why? because we can fill in the cage details, and the story doesn't hinge on them. The story does likely involve the significance of the "8" however, so that gets some stage time.
If you do a mirror scene just to describe looks, it is irritating and transparent. If you give us 2-3 details, we probably have plenty to fill in the rest as a composite of people we know/details our subconscious selects, and we can keep moving along nicely, instead of throwing the car into park out on the freeway just to count freckles. as a general rule, you can get by with way less description that you probably think you need--like i said, re-read a few books and see how much attention they really gave.
(by the way, I can think of a few books where description WAS over-done and it was annoying. the first Anita Blake book springs to mind, as I pull my long, black hair back and tie it behind my petite frame.....)