Mistake 1: not looking the part
If you don't want to blow the job at the first hurdle, find out the dress code of the organisation to which you are applying. Dressing outrageously or casually might demonstrate your individuality and get you noticed, but it will also show that you don't do your homework and don't care about approval from potential employers - you won't get the job.

Mistake 2: making sure that they know you are doing them a favour
Letting a potential employer know that the world and everyone in it owes you a living won't endear you to them. The employer hasn't built its business up for the sole purpose of giving you the perfect job, and it's not likely that (whatever you think) you'll be the sole answer to that employer's prayers. Keep your ego in check.

Mistake 3: preaching your philosophies on life
Don't deviate from the interview. Good subjects to avoid are the reinstatement of hanging, your sexual preferences or perversions, any religion (fundamental or not) - and any political issues. These (and others) are subjects which polarise views. They're great for the pub, but terrible in interviews.

Mistake 4: letting them know that you are looking for a stepping stone
Don't make it obvious that you're only looking for a way in and will shortly be looking somewhere else. No one likes to feel undervalued and nothing turns a potential employer off faster than being told that you're not likely to be around for the long haul - no matter what your ambitions.

Mistake 5: not researching about the company
One of the most common questions asked at an interview is: 'What do you know about our company and what we do?' If you're not prepared, it looks like you don't care about the job. Here are some common answers which are guaranteed to have your interviewer in awe at your stupidity:

Well, not much actually, I was hoping you would tell me."
" I haven't really had time to find anything out."
" I read your brochure in reception."

Mistake 6: telling them that your last employer was a jerk
Anyone who is thinking of employing you is unlikely to have any sympathy when you regale them with tales of the stupidity, insensitivity and general bad management which resulted in your seeking a new employer. They're more likely to think that you might be part of the problem.

Mistake 7: telling them how to run their company or how they could have better interviewed you
You might think that your last few years in academia have given you a clear insight into how things are done in the commercial world, but don't assume that these pearls of wisdom are just what your interviewer has been longing for. Theory is one thing, but most organisations (as you will quickly observe) are bogged down with the practicalities of reality, of which you have, as yet, no experience. Providing your view on how things could be better will simply demonstrate this inexperience.

Your checklist to ensure interview failure

1. Be late - minutes or hours, it doesn't matter, the effect will be the same.
2. Look a mess.
3. Show no enthusiasm.
4. Show no interest in the company (to really bury yourself, make sure that the only interest you show is to ask increasingly about company cars and expenses).
5. Have a negative outlook - on anything.
6. Don't ask them how you have done at the end of the interview (this could be mistaken for you wanting the job).
7. Don't tell them that you want the job, even if you really do.
8. Don't thank them for the opportunity of being interviewed.