Sim assessments
They are a waste of time if you put someone in an uncomfortable situation.
If you have a a 45 yr old candidate for DEC who has worked for a couple, or more, major airlines, he / she has obviously passed a conversion course and several LPC / OPC sims.
If the candidate is a TC on a particular type you can probably assume that given some time on the new type he / she will become a TC on that type.
If you are taking a cadet, put them in a sim that is representative of their experience level and see how they perform: don't stick them in a 737 / DC- 9 / BAC 1-11 and expect them to produce the goodies. I haven't flown a non EFIS aircraft for 15 years: if you put me in an analogue sim I would find it hard work.
An interview / chat is more revealing, particularly if it is done by a pilot or couple of pilots: who do you know, who have you worked for etc
Finally, a recommendation is the best way of recruiting.