We’ve all seen those cardboard signs on the roadside: They promise that you can make $5,000, $7,000, $10,000 or more working from home. Unfortunately, these are usually scams of some sort, jobs that would require you to work 24 hours a day to make $2,000 or less a month.

But how can you separate the scams from the legitimate work from home jobs? Sometimes it’s not easy. But there are usually tell-tale signs that can clue you in as to whether an offer represents a legitimate work from home job or a scam.

First, don’t believe any work from home offer that promises outrageous income levels. Think about it: If you really could make that much money working such a job, why would someone freely give away the information on how to land it? It doesn’t make sense, right?

Secondly, never trust a job offer that requires you to pay a fee to receive start-up kits or information packets. Either these kits and packets will never come or, if they do arrive in your mailbox, they’ll contain information that is either useless or readily available for free elsewhere.

A good rule of thumb to remember is this: Never pay any money to anyone promising you a work-from-home job. Anyone who requires you to send in money to qualify for a work-at-home job is a definite scam artist.

Look for contact information on a work-from-home ad, too. If all that’s included is an 800-number that connects you to a recorded message, something might be wrong. If the ad’s only contact information is an e-mail address, you might consider passing it by, too.

Legitimate employers make it easy for job seekers to contact them for information. Scammers try to make this difficult.

Finally, if a job offer is low on specifics, be wary. For instance, an ad promising that you can make $5,000 a month working from home three days a week is already suspicious. However, if that ad says nothing about what work you’ll have to do to earn that money, it’s doubly suspicious.

The unfortunate truth is that the majority of work-from-home jobs you’ll see advertised on sites such as craigslist or on roadside telephone poles are either scams or so unappealing that you won’t wan to work them. It’s difficult to find real, legitimate jobs that you can work from home.

The best way to find these jobs is to use your common sense. If an offer sounds too good to be true, you can bet that it is. If you can’t find any information about the work you’ll be doing, or if you have to send in a check to find out this information, steer clear, too.