Make sure that a recruiting firm asking you for personal information (as in willingness to move, salary, and so on) has a specific job in mind. Find out such details as information about the hiring company, the responsibilities of the position, its place in the company organization, and the relationship between the recruiter and the company. Ask for the position's job description. (You may not get one, but ask! You need the description to devise a compatible cover letter and resume.)

If possible, get these details in writing. If the recruiter is unwilling to give this information, you may want to end the conversation right then and there.