I used to write pieces aimed at clients, and never landed a single project based on that work. Once I started writing for colleagues, though, now they send me all kinds of leads and referrals because they know what kinds of problems I’m good at solving.
Interesting, @Eileen! Except for personal pieces, all my writing in the past 20 years has been for colleagues. Initially I did this simply to do it. I did it because I was excited about web design and wanted to share what I was learning. That is still my fundamental motivation, although, over time, “share what I was learning” mixed with an occasional desire to help positively influence the direction the field was taking (positively by my lights, anyway).
For me, this led not so much to referral jobs via colleagues (as in your case), but to being invited to pitch projects because someone on the client team—perhaps a front-end designer/developer, or someone in IT—liked the way my team and I thought about design for the web, and wanted to work with us, or at least consider doing so. The CEO might not necessarily have included us in the mix, but a senior designer/developer did—and sometimes we get the gig.
Writing to your peers and having work (or at least potential jobs) land in your lap as a result also worked for folks like Jesse-James Garret and Jeff Veen, back when they were running Adaptive Path. If you’re passionate about *craft*, you should write about craft. If what you say has some validity, it may bring in work.
For other people, the right direction is what @Jack suggested. Back when Jason Fried was running 37signals as a consulting design studio, he and his colleagues wrote as much about business problems as they did about design patterns—and the client services work flowed in.
The bottom line is probably, write about what you’re passionate about. Don’t necessarily do it as a means of getting work. Approach it as a writing challenge: you want to clarify your best ideas and communicate them as cleanly (and entertainingly) as you can. Think of doing this for the benefit of your chosen audience, be it business folk or your fellow designers. Aim for the prize of effective writing, and you may land the additional prize of paying design work.