Well, I have to admit that this has been a real case of trial and error. I have been interviewing and interviewing for almost 20 years and the following is what I have learned.
The interview process commences as soon as contact is made. If the contact was made via email, is the email well set out, correct spelling and grammar, respectful and polite. Check the time that it takes to respond to emails. This can begin to give you an idea about the reliability of the prospective employee. If it takes time for them to respond this can be an immediate red flag. From my experience, you can tell a lot about some one from the first casual encounters. For too long I ignored these first signs but overtime I could see the alignment of certain behaviour from the beginning.
It is so important that your trainers are on time. The last thing you need from a new employee is them constantly running late and even worse, not showing up. If your prospect cannot turn up to the interview on time, do not even consider them.
I have to say that nearly all the people that I have interviewed have no idea on how to present and behave in an interview. So many wore thongs and did no preparation. They did not bring referrals or copies of their qualifications. So, with not much to choose from, how did I manage to select and constantly train up so many new trainers. I got it wrong many times. One of the best ways that I used, was for the prospective new trainer, once they had arrived on time and could literally string at least 2 words together, I would get them in for an unpaid trial class.
This would show me if they were sincere and it would tell me plenty about their intentions. Again, I would get a good idea about their time management, how they work in a team, and whether they were motivated.
With many of the employees that I chose, in the end it usually came down to the intangibles and I found myself following my gut feeling more often than not. Some employees would stay for years and others would simply decide to not show up. Managing a team of employees can be a really frustrating exercise but as long as you are sincere and uphold your part in being a good boss, most of the time you will get it right.