I work for a consulting company which prides itself on its expertise, its young culture, and the talents of it's individual employees.
Each year we run a graduate recruitment program, targeting like minded individuals with a passion for one or more of our business streams, a great personality and loads of potential. I have interviewed all sorts of people for these (and numerous other) career opportunities over the years, and something that continues to amaze me is the simple mistakes people make when they could be making a good impression.
I can deal with people who cannot interview very well, unless they are sales people or professional communicators of some kind. I go particularly easy on fresh graduates. Yet, there are some things that indicate a lack of common sense. For example, when an interviewer asks about your 2-5 year goals during an interview for a permanent job, try to make it sound like you will be around for at least a part of that time. I had an answer to that question recently in which the young guy said he hopes to be working overseas in the short term. Our company is national only, and just minutes before this had been explained to him, along with the fact that we hope graduates will be with us for at least 3 years if possible.
My favourite though was a person to whom we sent a rejection email to. You know the ones, "Thanks for your application, we received many high calibre responses, please apply in future" etc etc. Most people don't respond to these except on the rare occasion to ask for specific feedback. A Masters student from Melbourne University thought he'd try to set himself up for next years intak. You know, get himself remembered and into our good books.
He wrote back, and I quote "you can kiss my arse, lol".
Nobody is perfect, and no employer would expect them to be, but write a good resume, present yourself professionally, respond thoughtfully at interview and avoid silly mistakes, and at least you know you did your best and you have a good chance.
One last thing. Also remember that there are probationary periods in most jobs. I had someone in a training session today who obviously forgot. He sat at the back of the class, had his headphones on, and fell asleep. Not a good look.