"How do we let the world know we now have a website?"

A client recently asked me that as we were getting ready to take his site live. If I could answer that question definitively, I'd be the richest man on the planet. I have a saying, "If you build it, they will not come…unless you are Apple."
There are several approaches that work together to build equity, but all take time (months, in the case of Google, which is why you should get even a few pages live). It's very cumulative, much like compounding interest. Here goes:

Online Methods

SEO (Search Engine Optimization)

You massage content on the site to make your site notable to the 800# gorilla, Google. You then adjust content based on analyics (records kept by Google on how your site is used). We do some things right out of the gate when we build the site, but this is an ongoing process that involves about a dozen key switches if you want to keep the site relevant and attractive to the search engines. If this sounds daunting, don't worry, we provide this as a monthly service. 

Rich Content

The huge trend today is "pull" or "inbound" or "content" marketing. I.e., you provide helpful information on your site or blog that gets indexed by the almighty search engines and may be served up in a search result. People come to you because they trust you. Push marketing (TV commercials or newspaper ads) is dead because we are living in a "post-trust era" (The Language of Trust: Selling Ideas in a World of Skeptics). Yes, you are giving away part of the store, but hopefully only enough to build trust and appear magnanimous. Work on developing a content strategy that makes you look like the good guys.

Social media

In order of importance: blogging, where you opine and provide more timely content; LinkedIn for more professional alliances; Twitter is used to point people to the blog and your site; YouTube channel, little informative talks (great SEO as well); and Facebook, your friendly face.

Offline Methods

Direct marketing

Direct mail, letters, newsletters to other industry members and maybe clients, of course, tastefully done.

Community involvement

Be active in the community, both online (related forums and blogs) and local organizations, related and not (chamber of commerce).

Public relations

News releases, public speaking, guest writing. 

Again, there is no silver bullet. It all takes time and commitment. Unless you can afford a couple of Super Bowl ads, and even then, no one will believe you.