Word of mouth is huge and make sure to be picky even when you are starting out. All it takes is one bad client posting bad reviews of you on The Knot or their blog and it can take you down. I would hang out with my family or go shoot for fun then have to do damage control from a bride who has unreasonable expectations.
i'm kind of suprised this hasn't been mentioned yet but have you networked yourself on
facebook yet?
While I didn't get my start that way, it has proven to work great right now for me. Some businesses use a "fan" page, but I decided against that and just use my personal facebook profile for everything. My thoughts are that my clients are not just buying my photo services, they are buying me for the day. I am very transparent with my facebook page and make sure to add all of my old college and highschool classmates as friends. Since I'm only 27, my target market is my generation of people right now. I throw some teasers from most of my shoots in my photo area's and then tag the clients in it. These photos then show up on their sites and are seen by all their friends who are also in that "getting married" age group. Make sure your facebook page is accessable to just about anybody, so join a ton of different networks so those cross-leads will actually make it to your page. On your page have a really nice bio that is honest about who you are and what your into. Put a link to your main webpage on your profile and update both your facebook page and main website often.
Of the 27 weddings I have booked for 2010, I picked up 13 of them off of facebook.
Whats great about getting clients off of facebook is that they aren't always budget weddings. I did have a few craigslist weddings when I first started and they were always "budget" oriented and had a different vibe to them. Not bad, but not really a spectacular wedding either.