What are the most effective ways to advertise on website for free?

Cathy, depends on amount of time you have. If it's free, it means it's pretty time consuming.

All the following resources are free:

For fast quick, results, you can post in classifieds ads. Some of the bigger classifieds sites:

http://www.enamul.info/links_classifieds.php

Smaller ones:
http://everydaybusinessonline.com/adsites.htm

My free classifieds & social website:
http://www.KaZuum.com

Blogs
Submit your site to blogs, maybe write an article about your product, and submit them into article submission site. And remember to put links to your website in those submissions.

Geek talk (skip if you don't want to get bored to tears)

Pending on how long you'd like to continue your site, it might be worthwhile to do directories submmission. Directories are like online phone books, business submit their site for approval, and if approved, gets listed. Don't expect traffic explosion from those, on average, each directories get you maybe 4 visitors per year, here is a list of 2200 free directories to submit to. It's a nessarily evil, but it has to be done.

Directories also gives you a bit of authority in google's search, google has this page rank thingy that bascially says, if a big popular site has a link to you, you gain a fraction of that site's page rank and you get indexed higher. But if your site links to crap sites, you get punished in the google search result. Idea of directory submission isn't just to boost your traffic, but boost your rank too. But smaller directories has less links pointing outside, so it's good to submit to them too because you suck up greater portion of their page rank juice.

You can also edit your title tags, if you have designed your site, every title tag on every page should be unique, and you should have keywords in your meta tags as well. Title tags and meta tags should be unique.

Social bookmarking site:
Those are like bookmarking services in which a user finds an site very interesting, they can mark it and have other users to see it. It's an extremely time consuming process, but one of the most effective. If you can get like 50 people to bookmark your site using stumbleupon, you site would get 500 to 5000 users a day just on those. If you get like 1000 stumble, better make sure you got enough bandwidth or your site will crash under the huge traffic coming.

http://socialposter.com/generator.php

If you find this useful, please signup at my free classifieds & social networking site and add me, Alex Wu, as your friend there:

http://www.KaZuum.com

KaZuum.com is a Free Social Classifieds Listings site where people can conduct transactions and network with each other: free classifieds, auction, barter, chat, profile & feedbacks, friends list, groups, event signups, and much more...

Current KaZuum ongoing advertising campaigns budget, we have 3 people on staff and some outsourced campaigns.

$15 to $30 a day on adwords
1000 ad postings for $50
800 article submission for $16
120 social bookmarking $40
2200 directories submission by interns free
400 classifieds ad posting by intern
Still fixing the title tags and landing page and site map to make it more search engine friendly

That's all, at least the white hat (legit) Search Engine Optimization method wise, there are a few more not listed. Black hat SEO methods I will tell you later if you are interested=)

Our site is growing at 10% a week for over 2 months now. Remember, always link your site as many times as it's reasonable =D

http://www.KaZuum.com