We bought our house about three years ago. We love it, but there were (and still are) a lot of superficial improvements that needed to be made to it. One of the main issues was the basement. We've gradually been trying to beautify it down there and just completed the re-do of the first of the two basement rooms.
The previous owners had absolutely destroyed the carpet down there - there were cigarette burns everywhere and it was absolutely filthy. Like, beyond cleaning filthy. It was gross. I can't even image how it got so bad. Pictures don't even do it justice.
In addition to the nasty carpets, the previous owners had put up an unappealing grey panelling on the walls, which had come loose and bowed due to the moisture in the basement.
We took down the panelling and ripped up the carpet. Then we hung drywall and cleaned the carpet residue off the floor. We decided to paint the walls a basic white to try to brighten the room a bit. After painting, we started on the floors.
After researching various flooring options, we decided to lay down a wood laminate flooring, which is ideal for all levels of a house, including basements. This room comes in from the garage and is bound to get a bit muddy and dirty, so we wanted something that would be easy to clean (as opposed to carpet. I think we learned from the previous owners' mistakes there).
We went with two underlayments to provide as much moisture protection as possible - this black plastic shown in the pictures below, covered by a special 3-in-1 moisture barrier, sound barrier, and cushioning underlayment (which I neglected to take pictures of).
Then we laid the laminate flooring. Somehow I forgot to take pictures of the finished product before we moved things into the room, but here it is, our newly re-done exercise room: