How to engage with an external headhunter
If you absolutely cannot find enough good candidates to interview, or have any doubts over the interview and selection process it might be a good idea to engage an external headhunter. This does not always have to be a headhunter. There are lots of hybrid and specialist offerings. Some suppliers can provide candidates only. Some suppliers can help with the interview and selection process only.
Define your problem very, very clearly
A well-defined problem is easier to solve. An external headhunter should be able to help you with this and I recommend spending the proper amount of time diagnosing the core problems. Inaccurate diagnosis leads to malpractice.
Beware the myths
More Recruiters Searching = More and Better Candidates. The converse is generally true. For example, recruiters will put minimal effort into your needs when they are competing with others.
Less/More Cost = Better/Worse Value for Money. Beware the low fee, beware the high fee; consider the total cost of hiring and retaining the candidate.
One Service = Another Service. Get into the detail with the supplier and fully understand their complete offering and process.
Provide incentive for the headhunter to solve your problems fully
Having defined the problems clearly and put aside your own assumptions, do you fully understand how the headhunter is motivated and how those motivators align to your needs? If the headhunter is motivated by earning a fee in the short-term and not the long-term success of your new hire and your career, there may be mismatches in expectations vs. reality. Make sure your needs and their motivators align. Everyone wins in a lasting partnership.
The price paid for hiring great people is often high initially, but should pay you a huge return in the long-run. If you do not sacrifice for your career, your career will become the sacrifice.