The depth and number of your folds really depends on your project and the size of your paper. I wanted to create a little fan to be used on a card or a tag ... so it couldn't be too big. I started with a 10cm x 10cm Washi paper with a very pretty floral pattern ....
As the paper is quite small my folds are only 1cm deep. Once the paper was folded I sqeezed it together, halved it
and glued it together in the middle.
As you can see it has already the typical fan shape. Squeezed it together at the bottom and secure with some twine - you can use anything suitable to hold the fan together (elastic bands, ribbon, thread, wire, ....) - decoration is optional
And just to show how that this technique is so useful to create wonderful decorations ... maybe you remember such long hot summer days when there was/is (almost) nothing better than a huge bowl of icecream with those wonderful decorations