Search Engine Optimization is a Long Range Strategy
Achieving high search engine rankings for popular terms is a long-term project.
In the beginning you research your keywords and set your plan. The more obscure keywords (those for which people search infrequently) will be easy to rank highly for as soon as your optimized site is indexed. The more popular the term the more difficult it will be to win the competition for a high position.
To quickly get an idea of what the challenge is for a popular keyword, just type a search term into the Google (or Yahoo or MSN) search box. Enter it without quotes because that is the way most people search. You will get back a page of search results and an estimate of the number of pages on the Internet that are indexed for that term. That number represents your competition.
Let's say the number of sites competing for your most important term is 36,325,700. Now if every one of them is hoping to be in the top ten search results there is obviously a problem. And search engine ranking algorithms are all about trying to solve that problem in a way that will actually put the best ten pages in the top ten search results.
Clearly, one of those millions of sites has to be #1 for that keyword, though. The question you need to ask is "What will it take for my site to be better than the 36,325,699 others?" And also "How long will it take for my site to be that good?"
These questions are answered by doing competitive analysis. When you look at the sites that are ranking in the top ten for a popular keyword phrase you will see that these sites normally have a great number of pages, and they have high link popularity. That tells you that if you want to compete you will probably need even more pages and higher link popularity.
Leaving aside the cost of developing a large number of pages and acquiring a large number of incoming links, there is the question of how long it will take to do that. Theoretically you could just pull out all the stops and knock it all out in a couple of weeks, right? Well perhaps you could, but that would probably not get you the high search rankings you expect.
The search engine companies believe that "normal" sites grow slowly over time. To a search engine, extremely fast growth and a sudden spike in the number of incoming links indicate that artificial means were undertaken in an effort to get high ranking. They consider this "spamming" the search engines, and your site will be penalized accordingly.
What this all adds up to is that unless you are only targeting very noncompetitive search terms you will need to look at natural search engine optimization as a long-term project. You need to start now and keep at it over time. While you may see some encouraging results relatively early on, you would do well to think of search engine optimization as a strategy that is going to start paying its greatest dividends after a year or so of constant, ongoing, slow but steady site improvement and link building.
Lest that sound terribly dire, depressing and hopeless, keep in mind that search engines like to see a new site launch with 20 to 25 pages of quality content, and a new site of that size will definitely outrank a new site with only five pages of equal quality content. Furthermore, although a brand new website cannot rank well for the highly competitive terms you may covet, you will find that people will start finding you through the search engines anyway, using a variety of search terms you had not thought of.
Getting traffic for some terms as soon as possible is important because search engines pay attention to which pages actually receive click-throughs from their search engine result pages. Furthermore, the search engines notice how long a visitor stays on your site before returning to the results page to try another site or do another search. These are indications that your website is worthy and important. These are indications that your website deserves a higher ranking so that people can find it easier.
Search engines reward sites that have a constant, steady influx of new, fresh content (that's why blogs typically rank well without any particular effort to compete for specific keywords). They also reward you for being around a while. A year from now after you've been paying your dues to the search engines you'll be feeling smug over your rankings and thumbing your nose at the new wannabe sites that hope to topple you from your solid position at the top.
But what do you do now for traffic?
The perfect complement to an ongoing search engine optimization campaign, especially for a brand new site, is paid advertising such as pay-per-click (PPC) where you will get immediate results for your efforts.