Suzy Sandberg earned her chops in the field of direct marketing. But when the internet made search marketing possible, Sandberg fell in love.

"For a direct marketer, search marketing was utopia," she says. It's not only controllable, it has tremendous ROI, explains the president of PM Digital, which provides internet marketing services for high-end retailers. And the technology just keep getting better, says Sandberg, who's been doing search marketing since 2001.

"I haven't seen any leveling off yet. All of our clients saw incredible growth this year, and I think this year will be better," she says.

"Clients just adore search; it's become the golden child. Google has pushed it to the No. 1 online source for every one of our clients," she says. "There's 30 percent natural growth every year."

Sandberg cautions, however, that a good search campaign will cost thousands of dollars a month, so it could be prohibitive for a startup. But there are always exceptions. Sandberg cites Moosejaw.com as a company with superb search marketing.

How does it work? With search marketing, you buy keywords on search engines (mainly Google) and pay a fee every time someone clicks on your ad. Using trademark terms is an obvious winner. If you're LL Bean, for example, you'd buy the trademark LL Bean. Generic terms are important, too, but the copy has to be specific to what you're selling.

In search, 80 percent of sales will come from 20 percent of your key words. But Sandberg says it's worth going after the so-called "long tail" in search--the more specific terms that are several words long. For example, "red cableknit cashmere sweater."

Says Sandberg, "Those words don't generate nearly as many as the top sales terms do, but in the aggregate, the conversion rate is going to be so much greater." Remember, you pay for every click to your website, whether or not it's a sale.

Sandberg's top tips for successful search marketing campaigns:

1. Have an expert manage the campaign. Work with someone who knows the ins and outs. PM Digital, for example, meets regularly with Google representatives, who let the company know what kind of changes it's making to its search engines.
   
   And Sandberg notes that the technology is always evolving. Google in particular continually enhances its service, she says. "In order to take advantage of those enhancements, you have to keep modifying your technology."
   
   PM Digital's technology includes an automated bidding tool, which Sandberg considers essential. Twice a day, the automated system receives performance data for client campaigns. Based on the way a keyword has performed in the past and based on the way it's performing that day, the program knows whether to increase the bid on a particular word--helping the company to a higher search engine ranking--or if the company needs to lower the price of a particular bid. The program automatically sends search engines what those new bids need to be.
   
   Another advantage to hiring an agency is that it likely has high-priced subscriptions to major search tools that help work out the keywords to target.
   
   
2. Make sure you have enough manpower. The more you put into it, the more you get out of it. "The potential is so huge," Sandberg says.