OK, OK, you all know how to fold paper. But there are better and worse ways to do it, and if you want a professional-looking publication, it’s wise to use good folding technique. It’s also faster and easier.
First off, you should get yourself a bone folder. It’s a simple, inexpensive tool that will save your little fingers a lot of pain and misery. And yes, it is really made of bone. You vegans can get a plastic version, though.
Hold your paper or stack of papers so that the inside is upwards and the future spine is facing you. Pinch it on both sides and bend the closer edge upward.
With your index fingers on top and your other fingers inside the book, fold the near edge over the far edge. DO NOT CREASE IT YET. Looking down on the fore edge (the part where the book will open, top of picture 2), line up the corners as accurately as possible.
Using your non-dominant hand (I’m a rightie, so it’s my left hand) press down on the fore edge and clamp it in place, so the corners can’t move out of alignment. Then, use the tip of your bone folder (or your finger, or a (closed) pen), put it on the rolled paper, and pull it towards you, drawing down the center of the fold, and crease just that center point.
Using the edge of your bone folder—and now is when you start to be really happy that you got one—put it down in that little crease in the center, and draw it out towards the corner, as well as towards you, in a sweeping motion. Remember to keep your other hand clamped down hard on the paper so it doesn’t shift.
Starting from the center again, crease the other side with the same kind of sweeping out-and-down motion. Voila! perfect fold.
One more thing:
If you are going to fold the paper again, there is another bone-folder trick that will come in handy.
When you are at the “sweeping” stage, go ahead and crease the corner where the pages are open, but stop your motion when you’re working in the other direction before you get to to the corner where you are folding the already-folded edge. When you get there, you’ll see that the paper has a tendency to want to bunch up there, and wrinkle, and mess up your nice alignment. (this is especially true when you’re doing a third fold). So. Put the point of your bone folder just inside the corner, press it gently into the crease, and draw it out towards you. This will help straighten out the wrinkles.
Now proceed with creasing the spine.
If the spine still doesn’t want to straighten out, before you crease it all the way you can pull it out a little and crease a little and then pull it out again, working it into the fold bit by bit. With just one sheet folded twice, or thin paper, you may not need to use this technique, but it’s very useful as the stack gets thicker.