I got into this two years ago by just opening shop and starting. At first I wanted to assist, but no one in my area was taking on new assistants and I am not the one to sit on my hands and wait for it to happen, so I just started.
I began marketing in Nov. of 2007 by sending out 350 postcards to the architects in my area every month, after I created a portfolio and website. Now I am sending out 1200 every other month to architects and designers in Philadelphia, New York and Baltimore (Philadelphia is nicely situated); I am thinking about changing this next year to once a quarter. I also send out monthly e-zines but to only those who want to receive them. Doing this can be a bit interesting, I have found that advertising in my e-zines does more harm then good; so I show one new picture, talk about things I see and read concerning the economy (because that is something I find interesting and studied in college, never be anything other then yourself), I also read a lot on marketing and include something that I read too. Last, I talk about the projects I have done in the previous month, but talking about it from my clients point of view, giving credit to them, not me.
In about March of 2008 (waiting for my postcards to start to sink in) I started making promo calls to those architects, creating a hot list of those interested in me, those on the fence, and those who had no interest. I still marketed to those who said they had no interest, just was not as aggressive (I did eventually get work from a couple of them). When I call, I ask them if they would like to have a brief portfolio review with me to just go over what I can help them with. You always want to talk about how you are going to help your clients, they are hiring you for their purposes not yours. After the meeting is over (and some of them are really short which is not a bad thing; remember they are busy people), I say thank you, leave, mail them a hand written thank you a week later, and then try to follow up with them every other month. When following up, I never ask for work, just how they are. I still try to meet with two new people every month.
Now after two years my name have gotten to the point where just about every architecture firm in Philly has one person who knows who I am and I have started to get jobs based on referrals, actually have one tonight from 6 till 3 in the morning. The first 10 months I went with out getting a single job from any one in my prospective base, so it was very difficult to keep on this path; the economy did drop though. But now after 25 months and with the economy coming back to life, I am at the point where I could live off of only my photography work (I am now at 40%), I am still keeping my other jobs like substitute teaching and teaching a class at LaSalle University.
I am now starting to get into marketing with Linkedin, which most architects are on, and Facebook/Twitter (although the decision makers at firms are not using this site, the future decision makers are). I am going to make a food portfolio (partly for fun) this winter and thinking of also branching off into travel and hospitality photography as well.