No Substitute For Solid Strategy, As New, Old America Firms Find; Yahoo retools its model as Wells Fargo deploys customer service effort.(A)(MANAGING A SUCCESSFUL COMPANY)

Byline: MARILYN ALVA

Born in the mid '90s at the dawn of the Internet boom, Yahoo enjoyed some wild and reckless years. Its main goal: Get big fast.

And it did, building out as many Web-based services as it could to lure site visitors and advertisers.

Until 18 months ago, nearly 90% of the company's revenue came from advertisers. Many were bubble babies -- dot-coms and other newborn tech companies -- that buckled under.

The wild ride ended. Yahoo's sales and earnings plummeted.

Now the company's sobering up.

It's a familiar story, and not just for the Internet. Companies rush new products and services to the market during boom times, only to suffer when things slow down.

Often the problem is the lack of a well-defined strategy, or any strategy at all, whether it's an Internet company like Yahoo or a …