1. The basic sofa
First, cut the paper to the size you want, and decorate it however you like. (I didn't because I was in a hurry, but you can go all out on this.)
Fold it in half like a book.
You have a sofa! I know, it's a bit of a ridiculous tutorial. You can make it fancier by adding armrests and drawing cushions, or by trying the following variation.
2. The fold-out sofa
This works well when you have more dolls than beds and are too busy to make a bed. All you need to do is add an extra fold to the above sofa.
Instead of folding the paper in half, fold it in thirds.
Fold one third back under so it looks like the basic sofa.
You can draw a pillow on the side you fold under, and have your furniture do double duty as a bed and sofa.
3. The chair
Start like the basic sofa - cut your paper and fold it in half. Cut it again until the chair is the size you want.
You can fold it over a few times to look like a lawn chair. I didn't do it on purpose (I was just re-using the same paper from the sofa), but it looks cool.
Cut some smaller strips that are the same length for the chair legs. I used two, but you can use however many you want.
Tape them to the bottom and you have a chair!
I hope you liked this tutorial, even though it was extremely basic. If there is anything you want a tutorial for, please, please, tell me in the comments, because I'm starting to run out of ideas.