Unless you are a wildly well-known and highly desired company at which to work (e.g. Apple, Microsoft or Google) then you have probably little more than the interview process to impress a top candidate.
No matter how fashionable or well respected your tech firm, a job candidate will get one chance to peer into the inner workings of your company. They wont judge you based on your cafeteria food nor on how friendly the staff is nor the lengthy (and probably completely inaccurate) job description. All that is a form of marketing.
A good candidate knows that and is exposed to it all of the time. No, they will judge you based on your processes. And the only process that you can't gloss over, hide or fake is the interviewing process.
A company's ability to interview effectively is the more revealing cradle-to-grave process that a candidate will see - very likely it will be the only one. And since this is a process that affects all others -- in that every person at the company was selected using it -- it is also the best way to indicate to the candidate what the overall company is likely to be like and how it functions.
A good hiring process reflects a healthy company using good processes and possessing good staff. A bad hiring process reflects a company with generally poor procedures and staff consisting mostly of those unable to find work someplace more attractive.
So the interview process must often convince a candidate that the unknown of your company is better than their existing, known position, and that it is better than the unknowns of potentially many other firms. Overcoming the "devil you know" issue can be very difficult, especially if that candidate already has a great job.
Ask yourself, If I had their job, why would I leave it to come work for me?
Vetting a potential candidate is not something that interviewers and the hiring process creators are likely to forget or overlook. But focusing so heavily on ruling out bad candidates will often also tell good candidates that this isn't a place where they are interested in working. Good candidates don't want to work in a place lacking bad people -- they want to work in a place full of good people. The two arent the same thing.
Having a good, efficient and goal-oriented interviewing process can be difficult, especially if your firm is large and follows traditional interviewing practices in a codified manner. There is no simple equation to running a great interview process. There are simple rules, though, that must be followed.
Every potential candidate that you will ever interview is full of horror stories from their own job hunts. Some are nearly universal, such as stories about how the human resources department sabotaged an otherwise perfect-fit position, while others are unique and surprising. Most process issues can be resolved, or at least mitigated, simply by taking the time to empathize with the candidates and see the process from their perspective.
Too often candidates go to an interview just to find that they are being interviewed by random people in the office who just happened to be available. Those interviewers have not seen the resume ahead of time nor are aware of the qualifications that they are seeking.
You wouldnt be impressed if the candidate being interviewed was late and unprepared -- why are we then surprised if top candidates are equally unimpressed when we are unprepared? We can hardly fault a candidate for not taking the interview seriously if we are not taking it seriously. But this is exactly how the average interview goes -- the candidate is far more prepared than the interviewing team.