How to Fold a Brochure
To fold a brochure, try dividing and folding it into 3 equal sections. Alternatively, you can divide it into 3 sections, with the middle section being twice as wide as the end sections. Then, when you fold the brochure, the ends will completely cover the middle panel. Or, you can do an accordion fold by dividing the brochure into 3 equal sections and folding one end forward and the other end back.
Decide on a paper size. Brochures are usually meant to be looked at quickly and carried around by readers. For this reason, most people use traditional letter-sized paper of 8.5” by 11” or smaller. However, you can go with a larger legal size, such as 8.5” by 14”, and count on the folds to minimize the actual final size. The larger your paper is the more difficult it will be to keep your folds straight. Do a half fold. This is the most basic type of fold that you can create. Position the piece of paper horizontally in front of you. Fold it directly down the middle to create two equal interior panels. The result is a brochure that almost looks like a book cover with no pages inside. Do a tri-fold. With the paper horizontal in front of you, use your ruler to divide the length of the paper into thirds. Mark where the 2 folds should be on the top and bottom of the page. Make the 2 folds and smooth them over with your hand. The 2 flaps on either side can now fold over the center panel. This is a particularly good fold for people who want to print a “surprise message” in the center panel, as it stays covered by the outside flaps until fully opened. It's also a good idea to keep the designs on the 2 outer flap covers consistent with one another. For example, it would look odd if the colors clashed in these two panels as they are directly on top of each other. Do a gate fold. Divide the paper into 3 panels. The first and third panels should be half of the width of the middle panel. So, take the length of the paper, divide it into fourths, and mark down the ¼ and ¾ measurements for folds. Make the folds and you'll see that the 2 flanking panels can completely cover the center one. Do an accordion or z-fold. Position your piece of paper horizontally in front of you. Use a ruler to measure out 2 or more equal folds. Make the first fold, to the far left, so that part of the brochure opens towards you. The next fold in the series the brochure should open away from you and so on. This will create an accordion structure that looks like a series of equal length zig-zags from above. This is a good structure for a brochure that needs to contain a large amount of information. It also allows for some flexibility of reading, as a person can start with that first interior fold or move around to the back panels directly from the cover. Do a double gatefold. Complete a traditional gatefold, as described directly above. Then, with the panels shut toward the center, divide the larger back panel into 2 sections. Make a fold down the middle of the page. The result will be a piece of paper that looks like a book, but has 2 hidden folded panels in the inside. Double-gate brochures are often used when a company needs to present a large amount of information. They can use the outer covers for a catchy design and still have plenty of room for details in the interior panels. This type of fold also goes by the name, “three-parallel gate.” Do a double parallel fold. Position the paper horizontally in front of you. Then, measure out and fold it at the halfway point. Turn the paper so that the open seam is to your left with the spine/fold to the right. Fold it once more right in the middle. This will leave you with 4 panels for information. Many people use this fold when they have a large design that needs to be shown in its entirety. When a reader opens up that initial fold, they will be presented with a full page of space that can be used for this purpose. Since there are clear back and front covers, you can also put less critical information on the back panel without losing precious space. Do a French fold. You'll need to complete 2 back-to-back half folds to create a French folded brochure. Start by folding your page right down the middle horizontally. Then, fold the remaining page in half across the vertical position. This will leave you with 8 same-size panels for content. Some people design French fold brochures with an image on 1 side of the sheet and the information on the other side. You can also just include content on the interior panels and leave the outside ones blank to serve as a total cover. Do a roll fold. After positioning your paper horizontally, divide it into fourths. As you mark where to make the folds, keep in mind that the left two panels should be just slightly larger than the right two panels. Then, fold the panel to the farthest right inwards. Crease the two folds on the right so that they wrap around the left side encasing it. The panels are the right side of the page initially must be a little smaller or they will not fit smoothly inside the other ones. This panel format is great if you want readers to be able to quickly move between different sections of your brochure. Get a complementary paper grain. When you consider which type of paper to choose, go with a paper that has a grain that moves in the same direction of your future folds. If you fold with the grain, you will get a smoother result. When you fold against the grain, especially with thick paper, you can have cracks along the spine. Fold on a flat surface. You'll want to fold your brochures on a table or other smooth, sturdy surface. This will let you exert a bit of pressure against the paper without worrying about the table wobbling and messing up your fold. After you've made an initial crease in a brochure, go over it once more with a ruler or stick to make the fold last longer. Do a test fold. Print out a few extra brochures that you can practice on before working with the final drafts. This gives you a bit more leeway to experiment with folding styles and make minor corrections, if needed. You can also set this test fold brochure in front of you and use it as a model for the others. If you are having your brochures professionally printed and then doing the folding yourself, make sure to order extra test copies. Check the edges of your images and text. Turn your folded brochure around in your hands and check the quality of the edges. Watch for spaces where the images or text bleeds through from one side to another. Look for any awkward white areas that might confuse your reader. If you notice these issues, you might need to modify your original design and/or choose another folding style. Check that all folds are straight. When have completed all of your folds, the bottom and top of your brochure should be in-line without pieces overhanging. If you are worried about keeping your folds clean, always start your crease at the bottom of the page, checking for alignment first before moving upwards. If you try a fold and you notice that the panels just don't sit right, it may be a matter of the panel sizes being slightly off. Try to refold these areas slightly more in one direction or another. When you make these adjustments you'll also have to keep in mind how these might alter the printing window or computer format for your brochure. Send your job to a printer. If you are concerned about the quality of your folds, you can always send your brochure off to a printer to be created, printed, and folded. This is an especially good idea if you need a large number of brochures in a short amount of time. Make sure to give yourself plenty of time between placing your order and the deadline. 
Decide on a paper size. Do a half fold. Do a tri-fold. Do a gate fold. Do an accordion or z-fold. Do a double gatefold. Do a double parallel fold. Do a French fold. Do a roll fold. Get a complementary paper grain. Fold on a flat surface. Do a test fold. Check the edges of your images and text. Check that all folds are straight. Send your job to a printer. 