When business is down and cash flow is tight, you have to reduce expenses to keep your doors open.

"For smaller businesses, panic sets in almost immediately when sales begin to slump or when payments from their accounts receivable slow," says Dennis J. Ceru, professor of entrepreneurship at Babson College and owner of the Strategic Management Associates consulting firm. "The natural tendency is to look for any and all places to cut expenses."

But cutting the wrong expenses can cost you money. Here are some expenses not to trim; followed by ways you can save money.

5 cuts that cost you
1. Hold the mayo, not the marketing. "A lot of businesses automatically cut advertising," says Victoria Colligan, founder of media company Ladies Who Launch and co-author of "Ladies Who Launch: Embracing Entrepreneurship and Creativity as a Lifestyle." "It's the easiest thing to cut. You know you can survive on your steady client base. But even during an economic downturn, you want to lay the foundation for expansion."

If you continue advertising, you'll be poised to pick up new customers when the economy begins to turn around. "No one knows when the economy is coming back," Ceru says. "When it does come back, it tends to come back rather quickly. You could miss the beginning of the uptick, when small businesses in particular have an opportunity to gain new markets, new customers or increase their market share."

Make sure your advertising reaches your potential clients. "If you do your research, you can find relevant, targeted Web sites to get your name in front of your audience without cutting advertising altogether," Colligan says. "Online gives you the ability to interact with your customer and allows for a much more targeted niche approach."

2. Don't terminate training. Training can save money and help you build a better work force. "Labor is cheap right now," Colligan says. Instead of hiring the most experienced, most expensive applicants, "Find smart people and then train them," she says. "If you've been doing your own books, you may be able to train someone else to do them for $10 an hour."

In addition to training work skills, train your people to build relationships with their fellow employees and customers. Teach employees to resolve problems by going directly to co-workers instead of gossiping or complaining, says Roxanne Emmerich, author of "Thank God It's Monday." For dealing with customers, have employees answer the phone with an attitude of helpfulness. Emmerich's example: Compare calling a business and hearing: "ABC Widgets, can I help you?" to "Thank you for calling ABC Widgets. This is Julie. How can I assist you today?" 

These simple changes, the kind you'd be tempted to scoff at, do make a difference and build your bottom line, she says. "I worked with a bank that hadn't grown more than 2 percent a year, then it grew 2 percent in one month," Emmerich says. "The CEO sent me a letter saying, 'It's a miracle.'"