The primary reason quite frankly I got into recruiting is that my experience with most recruiters while I was an employee doing marketing and business development (for 18 years) stunk. Really, getting a cold call from someone who wastes your time and doesn't have a clue what the difference between someone doing Business Development and Sales was pathetic.
So, my suggestion is to always put yourself in the candidates shoes. Be prepared. Don't waste their time. I think a lot of being a successful recruiter is building a successful relationship and reputation. I never had a single one with a recruiter during my jobs. Not a one.