I have heard of people doing it offline but I strictly do it ONLINE unless of course Im at a dinner party and someone comes out and asks what I do then of course I run it down for them. I advertise every way I can online, mostly I do it in free ways, but there are time when desperate times call for desperate measures and you really need to put money into your advertising. I belong to alot of forums, I always make sure I put my link in my signature. Most forums have a "promote" area so I always do it no matter how nervous I get about promoting it. Free classifieds, theres millions of calssified sites online. Write articles for people that are relevant to your site. If its a good article they WILL tell other people to goto your site. PPC sites. Word of mouth. If you have a good domain name like findcars.com you can get organic traffic. Site reviews, lots of companies, forums, blogs, etc have site review areas. You post your site, people goto it and they review it. But if they like it they will also come again. Safelists. God theres like a billion ways to advertise online I cant even list all of them.. OH one more important one... backlinks!
PM me for more info and Ill try to help out as much as I can

Kristi