The dating world can be hard to navigate, so it's nice to know that you've got a big scary man in uniform.

We're speaking of behavioral-analysis expert Greg Hartley, who's turned years spent in the army teaching soldiers to resist interrogation into a career educating civilians in the art of liar-spottin'.

Lucky for us, he decided to take his years of experience on the battlefield and bring it into the theater of love. He's written six books with co-author Maryann Karinch, including "How to Spot a Liar: Why People Don't Tell the Truth ... and How You Can Catch Them" and "Date Decoder: Military Intelligence Techniques to Expose What He's Really Thinking."

He took time out of working on his latest book to speak to me about lies and the lying liars who tell them ... whom we sometimes end up dating. Check out his list of easy, foolproof tips for figuring out if your storybook romance includes an unreliable narrator.

Love and War
Even though there's very little that dating and military combat have in common at the outset, Hartley feels that deep down, the skill of understanding the behavioral signs of a person's emotions can be useful in many situations. In "Date Decoder," he helps women figure out why they're attracted to certain kinds of guys and teaches them to evaluate both themselves and others more accurately. His says the biggest mistake that women make in relationships is that they will project what they want on a guy they're dating instead of observing what that guy is actually doing.

Put simply, if you believe your guy is a knight in shining armor, you'll ignore any tickles in the back of your brain that say things aren't quite right, and if you think your guy is just waiting for a chance to hurt you, you'll constantly be suspicious of his actions. Hartley encourages women to make sure they're approaching any dating situation with an awareness of themselves and open eyes.

I Saw the Signs ...
How can you tell if a man is lying to you? Hartley says that the best thing to do is to watch for two types of nonverbal communication: illustrators and adaptors. Illustrators are hand gestures, and when a man is lying, rather than gesturing as usual, he'll use his hands to barrier himself from you. Then, look for his adaptors, which are nervous twitches that help the man relieve some of the tension that comes from being untruthful. Rubbing fingertips, tapping legs, wiping under the eyes- these are all potential "tells" that your man is lying to you.

Hartley believes that eye contact is not always a great indicator of truthfulness, and that you should pay attention to either a total lack of eye contact or being stared down as a sign of trouble. He says that some people look to the left when accessing information (like "Where were you last night?") and look to the right to access the creative part of their brain (i.e., when they're lying), but that for some, this behavior is switched, so it's best to ask your man where his car is parked and then watch his eyes for a baseline.

Cold-Hearted Snake? Look Into His Eyes (but Also Ask Him Stuff)

So what do you do if you see these signals in a man you're dating? Hartley says there are three basic types of lies that people tell: lies of omission (leaving out the shady stuff), lies of commission (just making things up), and lies of embellishment (starting with a seed of truth but then adding a lie).

The best thing that women can do when they think they've caught a man in one of these lies? Ask questions. Get out the harsh lighting and wooden chair and ask for details, then ask for them again. Get him to tell you a timeline of how things happened, and then get him to tell you that timeline backwards. Hartley says even if you memorize an inaccurate timeline, it is very difficult to recount it in reverse order.

Hartley believes that anyone can learn the skills discussed in his books, but that some people will have a greater aptitude for reading people, and women often have that aptitude. Women have a great "gut," he says, they just need to be sure they're checking it often. He does caution that these skills shouldn't be necessary in a strong relationship: "If you are getting to a point that you're using my tools, you're already in trouble. A relationship should be based on trust." But for all those new courtships, or dates that just don't quite seem right, it's good to know we have a professional advising us.

Greg Hartley's books are available on Amazon. His most recent, co-written with Maryann Karinch, is "The Body Language Handbook: How to Read Everyone's Hidden Thoughts and Intentions."