too often we have people who have been scammed by people using our own listings at our office's own rental division coming in saying "well, I sent in the money! I want my keys!" and are left crying in our lobby when we tell them "we have never heard of you, where did you find out about that? we rented that property (x) months ago!"
Take the advice of Mr Carney-
Send nothing till you have seen the inside of the property.
Even if it was a legit listing, you (or a trusted confederate like a friend, or a real estate agent in your employ) still need to see the property before you even put an application upon it.
Rental fraud is very common and there is no legitimate reason for you to send money prior to viewing a place. If the home is listed here on Trulia, contact a local agent who does rentals and have them verify it's in the multiple listing service and is a legitimate listing.
Do not send money without fully verifying everything and seeing the unit. A deal that's too good to be true probably isn't and you probably can't afford to lose your money.
Communicating via e-mail with a request that money be sent prior to viewing the unit (or even after viewing the unit): Definite scam.
How to avoid that in the future: An initial e-mail contact is OK. But then you've got to meet the person. And don't be afraid to ask for ID from the person you're meeting. Never wire money to anyone. (That's kind of sad; it used to be OK. But now it's a red flag.)
Also, if the price seems too good to be true (you didn't say it was, but I'll bet it sounded like a real bargain), there's probably something wrong.
Hope that helps.