There are many types of booklets, from lose-leaf booklets to perfect and coil bound booklets, there is sure to be a booklet that fits your exact needs. The most popular type of booklet is the stitched also known as stapled kind. These booklets are available starting at 8 pages and can increase in page count by 4 pages. The most common page counts are normally those that are in multiples of 8pages- i.e. 16 page, 24 page, 32 page, etc...
Beyond their ability to provide ample content, the popularity of booklets is also due to the many options they have in the way of customization. Custom booklet printing can include anything from the type of stock the piece is printed on to more complex elements that provide that high-end touch like custom die cuts to embossing and foil stamping.
There are a few things that are important to consider when designing files for booklet printing. First, be sure you have laid out a mockup of your booklet prior to beginning any graphic design/layout. By producing a mockup, you will be able to easily plan for the exact number of pages your booklet will require, and in the off chance that the number of pages you need isn't divisible by 4 you can plan accordingly on which content you can add or remove.
Another thing to consider is the program you will use to do the design and layout. There are some really powerful programs, such as InDesign and Quark which allow you to do multipage layouts so that you can see exactly how your booklet will print. These types of programs are popular amongst graphic artists and typesetters. If you are new to booklet design and layout, and don't feel comfortable working in the more complex programs, you can always use a program like Microsoft Publisher or Word. Just keep in mind if you are planning on having your booklet printed by a professional commercial printing company, they might not accept these type of files, so it is best to check with them before beginning your booklet design.
Finally, go with what you know and see as common in other booklets, catalogs and magazines. For example; headlines, quote boxes, pictures are always good elements to include in your booklet. This will allow the reader to know what that particular page or section is about without having to dig to deep into the text content of your booklet. Another important thing you want to ensure you do in your booklet, albeit commonly overlooked, is to establish a common font package to use through the entire booklet. Multiple fonts can confuse and frustrate readers, so be mindful not to switch fonts from page to page. It is a good rule of thumb to have one or two fonts dedicated to titles and headlines and another one or two fonts dedicated to the actual content of the booklet- one for standard text and another for emphasized or quoted text.
Following these simple guidelines will help ensure your booklet printing is a success and keeps your audience engaged while reading through your booklet.