Doing your homework is the first step towards succeeding at interview, writes Karen Hainsworth

"A big mistake people make is not preparing for the interview," says Dr Rob Yeung, business psychologist and author of Successful Interviews Every Time (How To Books). "People think they can just walk into an interview and be themselves and talk off the top their head." But without doing your homework you're likely to end up kicking yourself and feeling that you didn't do yourself justice. "The candidates that do well aren't necessarily the best person for the job," he says, "but they're very good at getting job offers because they plan and prepare."

If you're a little bit rusty on your interview technique or you're struggling with your first few interviews after university, it's worth bearing in mind that organisations are continually evolving the selection process. "The way employers are assessing candidates is changing," says Rebecca Clake, Resourcing Advisor to the Chartered Institute of Personnel Development. "We do a survey every year on organisations recruitment and retention practices. In years gone by an interview would have involved a chat through your CV but these days many more companies are focusing on competencies."

Organisations identify a set of skills and qualities that are important to the job and ask questions based on how your past experience is relevant to the current post. And they want specific examples. 'Can you describe a situation where they might have demonstrated leadership skills?' for instance, or more awkwardly, 'Can you tell me about a time when you were working with a team that were having problems getting on?' The interviewer isn't interested in understanding how the emotional saga unfolded but how you coped. "They want to know what the situation was, what you did about it and the result. That's quite a simple structure and it's useful to have some reasonably concise examples up your sleeve," says Clake.

Some of the toughest interview questions are the ones that appear the most straightforward. "'Tell me a bit about yourself' is a very common opening question," says Yeung. "It sounds simple enough, but quite often candidates will spin a long tale." This is not the time to indulge your storytelling abilities, however. If you spend two minutes talking about your family background and early jobs that have no bearing on the post that you're applying for, you're missing an opportunity. "You could have spent two minutes talking about your recent career and your achievements," he says.

The key is to use every opportunity to put yourself in a good light.

The best way to re-assure an interviewer is to talk about your strengths and give examples. "First thing is to look at the job advertisement," says Yeung. "What kind of skills are they looking for? If they talk about a team worker, leader and customer service skills then you need to relate your strengths to those as closely as you can without lying." And look for key phrases. "If it says 'must be tenacious' then you talk about your dedication and hard work."

Though few interviewers look like interrogation personnel, some questions will feel like the thumb screws are being applied. Be particularly careful if your interviewer is a friendly figure who you're immediately reassured by. It's easy to be lulled into confessing all. That's not a good idea, particularly when you're asked, 'What is your greatest weakness?'

"This is a direct invitation to put your head in a noose. Decline the invitation," says Martin John Yate, ex personnel director and author of Great Answers to Tough Interview Questions (Kogan Page). There are various ways of dealing with this. "Take a weakness from way back and show how you overcame it," he says. You might, for example, say that when you first started work you found it difficult to multi-task but you've learnt to make a list of things to do every day, juggle projects and prioritise. You can then go on to describe how you've demonstrated excellent organisational skills in your most recent roles.

A friendlier but sneakier version of this question is 'what area of your skills or professional development do you want to improve at this time?'

"This is another tell me about your weaknesses question," says Yate. "You should try to avoid damaging your candidacy by tossing around careless admissions. One effective answer is to say, 'Well from what you've told me about the job I seem to have the necessary skills and background. What I would really find exciting is the opportunity to work on a job where...'" This not only reassures the interviewer that you can do the job already but allows you to show your enthusiasm for certain aspects of it.

Then there are those questions which are down right intrusive. 'Are you married? Do you intend to have children?' and 'Aren't you a bit old for this job?' are prime examples. You're not obliged to answer these as they're potentially discriminatory and could put you at a disadvantage when it comes to a selection decision. "There's a whole range of legislation on equal opportunities and diversity and its very important that interviewers are aware of the law," says Clake. You can choose to answer these types of questions in a way that reassures the employer about your commitment to the company or, even though it might seem confrontational, you can politely suggest the question is not necessarily relevant.

"Selection is a two-way thing," says Clake. "It's a case of the organisation trying to find out more about your skills and experience, how you match the job and how you are going to fit into the organisation. It's also an opportunity for you to find out more about the job, more about the company and the kind of people who work there. If you had negative questions at interview and you felt you had been asked inappropriate questions, it's for you to consider whether that's where you want to work."

If you do get a question that you're finding tough it's sensible and acceptable to think for a moment. Interviewers know you are only human and its better to take a pause and think rather than start gabbling and realise a few minutes later that you really wish you had said something else. If the worst comes to the worst you can always make up for a duff answer by asking intelligent questions at the end.

When you're released from the interview, be gentle on yourself, advises Clake. Do the preparation, do the best you can, and once it's over, put it out of your mind. Regardless of whether you receive a job offer, ask for some feedback. "Find out what went well and how you could have done better. Asking for feedback can be really helpful and you can use the information next time round."