1. Web Marketing Relationship Management – Existing Customers
Blog, newsletter, postcards, etc.
Organic Search
Keywords typed into Google, etc.
Adwords
Pay-per-click ads on search sites.
Web Links
Conversion
Links to your site from other sites (e.g., blogs, media).
Ad Placement
Paid placement of ads on specific sites.
Affiliates
Referrals by incentivized partners.
Abandonment
Direct Access
Your domain typed directly in the browser.
Sometimes…
Conventional Marketing
Direct mail, print advertising, television, PR, demos, etc.

2. Search Engine Optimization
Rule 1
Make your site great.
Lots of relevant information.
Clear and organized.
Direct link structure, plain text, lots of key words in first 200 words on site.
Then,
As many relevant inbound links as possible.
From high-credibility sites (e.g., The New York Times, upenn.edu)
Post credibly on forums.
Page names include search terms, possibly hyphenated.
Domain names include search terms, possibly hyphenated (but don’t look spammy).
Avoid bad neighborhoods (who else is hosted on your server?).
Avoid duplicate content on multiple pages.
Images are tagged with keywords.
Go ahead and use webmaster tools provided by Google (e.g., site map).
Good resource:

3. Ad Words
Google is the main event. Bing essentially identical approach, interface, etc.
Can definitely buy traffic – but will it result in profits? Tune and experiment using Google tools.
Yes, probably use your own brand as a paid search term.