I have written a couple of technical books and what works for me is to blog about it. This would be the step after the outline step in the article.
If I can't write 10 or so blog posts on the topic, can I really commit to a full book? For me, the answer is no. There's a lot of grinding in writing a book, so you'll need intrinsic enthusiasm on the topic to finish.
Leanpub is a nice way to get feedback as well (there's nothing that indicates commitment like $$), but writing blog posts (and sharing them on places like HN or a forum about the technology) can get you feedback.
If I can't write 10 or so blog posts on the topic, can I really commit to a full book? For me, the answer is no. There's a lot of grinding in writing a book, so you'll need intrinsic enthusiasm on the topic to finish.
Leanpub is a nice way to get feedback as well (there's nothing that indicates commitment like $$), but writing blog posts (and sharing them on places like HN or a forum about the technology) can get you feedback.