Although I learned by falling mugu once for scammers, once bitten twice shy.
Here are some tips.
Ask about the organisation, especially if they are using a personal e-mail addy like yahoo or hotmail.
Reply the scammers asking for further information.
Call the numbers of the organisation they are claiming to recruit for, by looking it up on the internet and look for their address.
Smell a rat when they ask for money.
Be suspicious if you never applied for the position, ask them how they obtained details about you.
Find out the exact address.
Beware, it might be an attempt to kidnap, especially if its a far out place in a location u do not know or in another state.
Dont seem to eager when talking with them on the phone, even if u are desperate for a job.

Note: If ur cv is on the internet, ppl can easily use the information there.

Good luck