Follow this site and get a feel for what programmers are like.
Ask those at the hiring company lots of questions about what they want in a candidate, the demands of the positions, the corporate culture, qualifications, soft skills, anything.
When dealing with candidates that already have a job, understand their current situation. You need this insight if you are going to get qualified candidates (who probably have pretty good jobs) to switch to this firm.
I know a recruiter on the US East Coast, who decided to give up on emphasizing: free lunch, fooz ball, casual work environment, rent subsidy, exciting work, blah blah blah and just flat-out let candidates know they start at 200K.
Follow-up on your contacts. Nobody wants to wait for bad news or have to call back when a returned call was promised.