The Surprising App That Worries 'Mad Money's' Jim Cramer

Your business is always just one bad Yelp review from shutting down, Jim Cramer warns.

"Your enemy and your friend is [the smartphone]," the host of CNBC's Mad Money and founder of The Street said on Saturday during Martha Stewart's fifth annual American Made Summit in New York City. "There's an app that will save you and an app that will destroy you."

The former hedge fund manager also runs two small businesses -- an inn and a Mexican restaurant. He and Stewart both emphasized the importance of small businesses in the U.S., with Cramer referring to them as the "heart" of the economy.

Related: Feeling the Sting of Recent Rotten Reviews on Yelp?

Here are the money man’s top tips for small-business success.

1. On first hires

"The number one thing is your first hire has to be your accountant," Cramer said. "If you bring in an accountant first, 62 percent increase in odds that you'll succeed."

2. On partnering with friends and family

If you're going into business with a friend or family member, assume it will end badly, Cramer said. "You have to presume everything ends in divorce," he said. "Of course you start with love, but you have to have a document in case something goes wrong. Figure out what happens if [the business] fails or you hate each other."

3. On financing your business

You should always opt for a loan from a friend, family member or bank instead of seeking an angel investor, "who may want your business," he said.

4. On knowing your potential enemies

All business owners need to put a lot of thought into who can "eat" or "stop" them. For example, when Cramer took over his inn, he made friends with the local fire department because he figured there would be a lot of false alarms.

Related: Martha Stewart: The World Wants Your Unique Product. You Just Need to Find the Right Partners.

5. On finding a location

No surprise, but Cramer stressed the importance of location. "Traffic is the most important thing," he said. He pointed out that his restaurant is located near an F train stop, which equates to a lot of foot traffic.

6. On web presence

Cramer also warns that you should not skimp out on your website. "If your website looks amateurish, people will think you're amateurish," he said.

7. On social media

The Mad Money host does all of his own social media, since he doesn't trust anyone else to do it for him. He said that Twitter is "relatively ineffective," although he frequently tweets. "Everyone has to use it," he said, "but the return on investment isn't there."

Related: 101 Businesses You Can Start With Less Than $100

8. On avoiding the taxman

Payroll is another area in which business owners need to be vigilant, and he recommends using a service to avoid attention from the government. "If you do it yourself, you're an easy mark," Cramer said.

9. On making it up to customers

Disappointing a customer could lead to a bad review, which could sink your business, Cramer said, so it's important to make things right. "There is a trick that works with Americans," he said, "a free beer."