Mobile technology companies hoping to raise venture capital in a slowing economy should act like they're on a no-frills backpacking trip and be prepared for tougher scrutiny of their spending patterns, said top investors Wednesday at the Mobile Media Investor Conference in San Francisco.

"I think I did Europe on $20 a day," said Rich Wong, a partner at Accel Partners and arguably the most bullish mobile-tech investor in Silicon Valley. "This is what [venture capitalists] are asking now."

While VCs are still looking to invest, Accel and other firms are looking for start-up companies that can operate for at least the next 18 months on $50,000 to $150,000 per month.

"If they are interesting, and can stay within that burn rate," they have a better chance of getting funding, Wong said.

Other VCs at the conference agreed they aim to keep investing in budget-minded mobile tech start-ups through 2009.

Storm Ventures, an early-stage firm that has backed mobile start-ups like AdInfuse Inc. and Cellfire Inc., invested in six or seven mobile-tech companies in 2008, senior associate Ben Choi said. In 2009, the firm will likely back four to six more, he said.

Sharon Wienbar, a managing director at Scale Venture Partners, said her firm usually backs 10 to 12 tech and health-care companies each year. But in the second and third quarters of 2008, the firm took a break from all investing to let the smoke from the current economic problems clear.

In 2009, Scale will likely go back to funding 10 to 12 start-up companies, she said.

Wienbar and Choi both said that start-ups need to keep their burn rates within $1 to $2 million per year if they expect to stay afloat.

If companies can stay within those constraints, "There should be some break-out winners in wireless broadband," Wong said.

Among the types of mobile start-ups VCs consider most promising are those providing security and systems management for business applications -- which are seeing explosive use since the release in the past year of several new smart phones.

And mobile advertising -- a promising area littered with many failed ideas -- also has some "sweet spots," according to Wienbar.

"Great companies came out of the last bust," she said. "Direct-response advertising, like what Google does, came out of that time. A mobile direct-response ad platform" would be a promising bet, she said.

Additionally, VCs keep a sharp eye out when developers from top-name tech companies like Apple Inc. leave to start their own companies.

"These guys have the keys to the castle," Choi said.

Investors still have faith in apps for smart phones, panelists said, but are looking for better monetization plans than simple download fees, which have been decreasing to attract more users.

Game-maker Tapulous Inc., for example, the developer of the popular Tap-Tap Revenge and other games for mobile phones, now charges artists who want their songs included in the game. The company also charges users who want to add more songs to the game.

VCs are also looking at start-ups with a product that can be sold in the fastest-growing emerging markets for mobile tech. Investors said these markets are in South Africa, Indonesia, India, Brazil and China - countries that are seeing a huge increase in consumption-oriented, newly middle class residents.

Perhaps most importantly, as times get tougher, start-ups need to develop products that address specific market needs, or which fix a nagging problem.

"The build-it-and-they-will-come business model is getting harder," Wong said. "Where are the rational business models?"