if someone's interested in journalistic writing, but only as a secondary source of income, how does one go about building a portfolio?
I think I had mentioned this in your previous writeup... but anyway, I'll do it again here. (Just so you know, I've written two technical computer books myself so this advice, IMHO, is credible and good.)
First off, identify what you want to write about. It sounds like you've already done that, which is great. Next, start up a Web site of your own with articles on that topic. (www.SimmonsHouseOfLinux.com is avavilable <grin>.) This will serve as some practice for writing, you'll get some good feedback as visitors read your articles, and it will provide a place you can point potential employers to.
Once you've done that, contact book publishers and offer to (free of charge) do some technical editing for books in the field you're interested in. Very rarely will you get turned down, especially if you can point to your site and say, "See, I know what I'm talking about." This will do two things: it will help with networking (you'll get to know some editors in book publishing companies) and it will get you some experience that you can reference in a resume. I know you are interested in jounalistic writing, not books, so after a few tech reviews, ask the editors if you can write an article for their site. (Most publishing companies have a decent Web site with articles and such...)
Next, visit Linux sites and offer to write articles for them. Point to your site for examples, the books you tech reviewed, etc.
Next, contact Linux magazines (via their site or whatnot) and present your portfolio - your site, articles on independent Linux sites, your tech reviews... use your editor/Web site friends as references, submit a writing sample, etc.
While volunteering to write on sites like linux.com is rewarding, a paycheck, for me, is a lot more rewarding
Yeah, I agree, but you may need to do some volunteering first to get some name recognition, experience, and contacts. Imagine if you write a monthly article for Linux.com that a lot of people read... your name will get out there. When you go to a magazine offerring to write an article for $$$, you can say, "Hey, I'm so-and-so, and my articles on Linux.com have gotten over X page views."
If you want to write books, also look into getting a literary agent. I never did that, but probably should have. Also, be sure to always have a lawyer review all contracts before signing! :-)
Money is in some respects like fire; it is a very excellent servant but a terrible master.