Research the topic you would like to write about. Spend time getting your hands dirty and learning the task yourself so you are able to relay your own experiences and techniques to readers. Also consider interviewing experts on the subject.
Create an outline of each step in the book. You can break up the steps chapter by chapter and go even further, breaking down each chapter into more detailed step. Organization is key to writing simple, easy-to-understand terms.
Start the book by highlighting the necessary tools your reader will need to learn the tasks you're preparing to teach them.
Begin each chapter with an identifiable story about someone else's experience when learning the task you are writing about. You might want to petition and interview a small number of people and include their stories in your book.
Outline each chapter for easy consumption. Start out by telling the reader what they can expect to learn from that chapter and how you plan to teach it to them.
Write each chapter in clear, identifiable language. If there are big words, break them down so your reader can understand and identify with the terminology.
Provide clear graphs, charts and images demonstrating the technique beside the written explanations. This will allow the reader to refer to and compare their own progress visually.
Include lists of resourceful materials that the reader can move on to after learning the basics. Add book recommendations, websites, foundations and organizations so they can get more involved with the subject.