One of the most traditional routes to getting a non fiction book published is to write a series of articles first - something that can be expanded and adapted into a book. The first hurdle here is to persuade an editor to let you write a series of articles in the first place - but it's not impossible. Certainly, telling a potential book publisher that you have a series of related articles already does your pitch no harm so I'd recommend that you give it a try.
The way to increase your chances of getting a series is:
* Write down your ideas and separate them into specific headings that you can work into several different articles.
* Give the editor a flavour of why you should be the one to write a series: details/examples of your previous published work (whether paid for or not).
* Provide a basic outline of what will be in each article and how they relate to each other.
* Give the editor an idea of the kind of experts you will be approaching/have approached to be in the article and in what way they will contribute.
*If you are an expert with the relevant knowledge, qualifications and experience, all the better. But if you are not - you soon will be by all that hard researching work you are doing and the networking with people who have you'll be doing!
Once you have all the relevant information and have written your pitch you can send it in and see what happens. Preparation is key here so be as specific and professional as you can be. If a potential editor knows they are dealing with a writer they can trust to give them good copy it bodes well for future relationships with potential publishers.
Give it a go. You never know!