I used to talk about the 3 C's - ' Character, Competence and Chemistry' when we hired people. It trips off the tongue and there's nothing fundamentally wrong with wanting these traits in a new hire.
But to be honest I was kidding myself .. it's almost all about character.
I don't really know how someone is going to fit into our team when I hire them but one thing I do know is that if they seem to be open to change, flexible and committed then they are going to have a good chance, and any gaps in their ability are going to be easy to plug.
In fact my partner and I talk about the Pisys 'gene', a trait which is about 'getting it', quickly coming to terms with a flat management structure, a variety of projects and a lot of responsibility, generally within week 1.
We're not a 'normal' company in many ways (nice ways !) and we find that the people who 'get it' get on very well and stay for a long time - I like that, some of our staff have been with us for 20+ years.
Formal qualifications are a good starting point but I'm as likely to hire a former carpet fitter who has devoted himself to learning how to code as I am to employ a comp sci graduate who can show me nothing except a piece of paper. I wasn't always like that, degrees were very important to me but they're only part of the picture these days.
Of course we're obliged by law to have transparent and repeatable criteria when interviewing so that we can ensure that we aren't unfairly discriminating, so we have a standard outline which allows us to score candidates on the key elements we are looking for - but the question we're really trying to answer is ' will we get on with this person, will they be committed and be a good learner'
We are pretty specialised so technical experience in another company isn't necessarily going to be a huge help - it's a good baseline to understand the commonly used tools, but we have our own way of doing things which we need our people to get a handle on
Have we made mistakes - oh yes, but on average we've made more good choices than bad ones.