I realize this probably isn't Exactly what you're looking for (because it is a bit of cold water in the face, potentially), but hopefully you'll find it helpful anyway... There are three main reasons that photographers get their work published:

1. They differentiate. What makes your photographs different than every other photographer's photographs? If you don't know what the answer to this question is, you will simply not get published. The cold, hard fact is that in all likelihood every photo editor you will ever come in contact with has seen exactly what you are offering a thousand times... unless you figure out right now before you start taking more pictures how your photographs are going to be different than every other photographer out there and then take all your pictures that way and work that angle to the bone.

   The thing that makes your work different cannot be:

   • The location or subject matter of your photographs is so unique and different (unless you're taking pictures on Mars, you don't have the market cornered on unique locations or subject matter)
   • The technical proficiency of your work (Everybody's work will be as technically proficient as yours... Your work must be technically perfect just to be in the game at all)
   • The cool post-production effects you use (Leave the heavy Photoshopping at home, only amateurs do more than basic color correction, cropping, levels, dodging and burning)
   • How pretty your pictures are (Anybody can take a pretty picture. If your picture isn't saying something more profound than 'I'm pretty!' you're going to have trouble getting published)

   What does that leave for you to differentiate yourself with? Figure that out and you'll find publishing success.

2. They network. Sorry to say, but the old cliche is true- it isn't what you know, it's who you know. Photo editors are human too. If they have the choice between someone they know and an unknown, most will choose the known quantity every time. The vast majority of editors are not out there 'lookin' to give a new guy his big break.' So how do you break through? Become known. There are a couple of ways to get known, but the absolute best way is to follow the advice in point #1 so the work stands out in the crowd of photographs that the photo editor will be looking through.

   Submit often, submit only your best stuff (never, never, never submit even a single photo to anyone that isn't of the highest quality. Never. Did I mention never?) and follow up with robot-like consistency. Ask for assignments. Even if they never result in publication, assignments can demonstrate that you're reliable and a 'go-getter.' Ask what a publisher has coming up in future issues and then take pictures that fit the requirements. Become someone who the photo editor (or at least the photo editor's receptionist) knows by name. If you've got a history of submitting exceptional work consistently (even if there wasn't room to publish it at the time you submitted it) editors will start to remember your name. And then one day you'll suddenly find yourself on the inside, instead of the outside.

3. They work their @ss off. It's very simple... Part-timers don't get published. Now you can point me to dozens of part-timers who have been published once, twice, maybe even a few times over the course of a lifetime, sure... But you will never find a part-timer who publishes on a regular basis. "Now wait a second," you may say... "I can't afford to quit my job and be a full-time photographer! So there's no hope for me?" Ah... Here's the secret (minor secret though it may be)... Work your full-time job, and also work as a full-time photographer. Do that until photography becomes the full-time job.

   Now I say all of the above knowing full-well that you stated you weren't interested in getting paid, but another cold, hard truth is that part-timers may (or just as often they may not) get a few lucky shots published over the course of their life, but full-timers are working every day to generate enough output that they're no longer relying on luck to take the sorts of photographs that belong in publications... and there really isn't a whole lot of middle ground, unfortunately. If publication is your goal, then it cannot be reliably achieved as a part-timer.

Here's the thing... The above may sound harsh, or like a whole lot of work, and potentially it is both. But I've been a working professional photographer for 15+ years now and I'm speaking from experience when I say that you don't need a self-help book's worth of advice to get where you want to be. If you work these three angles like they're your last hope on earth you will become successful eventually (and probably sooner rather than later), and if you don't... You probably won't be. I've seen plenty of people go both ways over the years to know that the odds will favor you, or be against you purely based on how hard you work.