The interview is only part, although a crucial part, of the process. The first part is that letter of application that you send in addition to the CV and/or application form.
That letter/CV needs to get in the right pile: 'yes, worth interviewing'; 'maybe'; 'no way'.
Your letter/CV has to wear a suit, not be scruffy, and allow the message about you stand head and shoulders above the competition. A spelling mistake should be avoided like a stain on your trousers: it draws attention to itself and undermines the most expensive of suits. Your letter/CV should be engaging, clear and easy on the eye.
Getting onto the short-list is, of course, only like winning the semi-final, necessary but not sufficient. Its at the final that you win or lose, and have to recognise that you will be one of around four to six candidates (numbers vary) that the interview panel have to choose between.
First impressions do matter but the interviewers, if they are any good, will be trying to get beyond that, to understand 'where you are coming from, and where you think you are going', and how that fits with the job they want doing, and how you will fit into the team they already have. Strongly recommend that you do some research about the company and the job you are applying for, and let that come through in your replies, in an ordinary way.
What you should be aiming for at the interview is to get onto the 'employable' list. Whether you are first or second on that list depends upon the competition. Even if you dont get offered that particular job, they may have you in mind for another.
References are a bit like the penalty shoot-out, in that they matter when no clear result emerges. But they matter even if you are the best candidate. Like a 'best man' at a wedding, your referees(s) can make you look good or bad - so choose them carefully.
And yes, do wear a good (enough) suit.
In the last twenty years, I have been on the interviwer's side of the table well over 50 times, but less than five times on the interviewee's side (both successfully and unsuccessfully). Both sides have work to do, and want the best result. Both sides should enjoy the experience. It matters to both.
[edit: and remember to proof read that letter/CV several times, as I should have done for this posting!!]