It's important that you figure out exactly who you're communicating with before you write your guide. In most cases, the audience will probably be the uninitiated. Your readers have a problem and they're coming to you for a solution. They want to know more about something, and you have the knowledge they are looking for.
Knowing who you're writing to, and what they're looking for will ultimately assist you throughout the DISTILLED process we're highlighting throughout this guide. Deconstructing this information before even beginning to map your ideas will expedite the process of creating a guide immensely and ensure that it is useful to the people who are going to use it.
Some questions you should be asking yourself:
Determine your audience, and then move on to establishing exactly what you hope your audience will learn by reading your guide.