What Is The Purpose? Determine what the purpose of the documentation is such as work instructions, vendor instructions, knowledge base or other type. This will help you define the content, the format and in some cases the media you will use.
Who Are You Writing For? Knowing who will be reading the documentation will help you determine the depth and word usage. You want to write the documentation at the level of the person reading it.
Collect Information: Even if you are an expert in the area gather all of the information you can find on the subject. You may need to interview or get the assistance of others to help you gather the needed information. Manuals, user guides and online resources are very useful.
Write an Outline: Start with an outline of the document identifying the different sections of the document. This will help guide you as you fill in the blank spaces with more detail.
Write The First Draft: Working from the outline begin to fill in each section with details. Don’t worry about formatting or editing at this point. Here you want to get down all of the information that will be in the document.
Revise and Format: Now it is time to polish the document and format it. A good rule of thumb is you will end up removing more than you add if you wrote the first draft correctly. Wait until you have a final draft before you format the document.