First off, look in Seek and the legal press – who is advertising a lot? What is the quality of the ads they are running? Are they well written?
Next, look at the recruiter’s website- what is their firm’s recruiting philosophy? Do they follow ethical guidelines? Have they written any articles on career-related issues? Is there any more information about them on a website which tells you more about their recruiting philosophy?
Arrange to meet them for a chat, most recruiters are happy to provide no obligation/pressure advice to you over a coffee.
Talk to your friends or trusted colleagues to see if they know a recruiter who has assisted them in the past and provided a good service.
The most important of all of these though, is word of mouth.
It’s a recruiter’s good name that makes them good 🙂