Have an idea!
If you can't think of an idea for a book or other product, get some help by asking contacts, colleagues or clients. Failing that, get some brainstorming software such as Mind Manager. If none of that helps - go for a long walk, forget everything and let your subconscious get to work.

Think
Once you have an idea, just let it mull over in your mind. Jot down associated ideas and thoughts. Produce a mind map, if that's your thing, or a list of ideas and thoughts related to your original product concept. Always have a notebook with you so you can jot down ideas as they strike you. That means keeping the notepad by your bed so if you wake in the middle of the night you can record the idea and go back to sleep!

Set up an ideas bank
Get a folder or a concertina folder that is divided into sections. Label each section for one of the themes your book or product will cover. Put your notes into each appropriate section of the folder. As you read newspapers and magazines, tear out any useful information and bung it in the appropriate section. As you browse web sites and see useful pieces of information, print them out and store them in your folder in the relevant place. Don't judge what you collect; if you think it may be valuable, just collect it and file it.

Talk to people
Don't keep your book idea a secret. Talk to anyone who you know who could help provide you with useful information. Interview relevant experts and chat with colleagues and contacts to collect extra material.

Produce an outline
Having written some notes, collected some background material and chatted to people you should now be able to come up with an outline for your product. At first, start with a broad outline of the main themes you will cover. These will make up your chapters. Now, take each theme and subdivide it into the particular points you want to make or things you want to discuss.

Write
You don't have to start at the beginning. Choose any of the small parts of any chapter and write as much as you can about it. Don't worry about the grammar, the spelling or the niceties of your literary style at this stage. Just write whatever comes to mind about the specific subject you have chosen. Once you've done that, select another part of your detailed outline and write about that. Let's say you have 10 chapters each with five sections. That's 50 sections you need to write. For a 30,000 word paperback of around 120 pages, that means you need around 600 words per section. By taking it a section at a time it is more manageable. If you only did one section per day, you'd have a complete book in only seven weeks.

Edit
Once you have your sections written, you'll need to pull them together. You will also need to write some connecting paragraphs and sentences to make things flow.

Get some help
Having produced your first draft, get someone else to read through it and suggest changes. Do not be precious about your work. You are seeking their changes; you want them to change things. Otherwise your material will not be from a reader's perspective, making it less attractive. Once your reader has suggested changes - make them! Then tidy up your work.

Get some more help
Now get someone else to edit your work. They need to go through it with a fine toothcomb, looking for inconsistencies, poor argument and lack of detail or clarity and so on. There are plenty of freelances who will do this from the Society for Editors and Proofreaders (http://www.sfep.org.uk).

Check and re-check
You are on the home straight now! All you need to do is check the work of the proofreaders, make sure that your final text is correct. Stop thinking you could have written a different or better book. Just check this one is OK.