Organic search is important, and will really pay off in the long run. But for instant results, many people turn to SEM programs based on PPC. (That's Search Engine Marketing based on Pay Per Click).
Basically you set an ad budget and let something like Google AdWords spend your money driving customers to your website. For a few pennies a day you can realistically start getting customers immediately. Even if you pay more, targeted online PPC advertising still gives you a better ROI than traditional advertising.
When you pay per click, you only absorb a cost when an interested person clicks on the ad. You can further refine this by only showing ads in selected geographic locations.