The informal style of interviewing has its advantages and its drawbacks for both parties.

In this style of interviewing, the employer has not prepared any questions but wants to have a general dialogue with the candidate about the role and requirements, letting the discussion flow naturally.

There are several possible reasons for taking the informal approach to interviewing. It could be that the candidate’s resume clearly qualifies him for the role, and the employer is merely assessing the individual’s potential to fit into the culture of the organization.
In many creative work environments, such as advertising agencies, “fit” is often more important than professional background.

On the one hand, a friendly, conversational approach by the employer immediately makes the candidate feel at ease. This is a welcome relief from the stress of difficult questions and challenging situational scenarios.

On the other hand, the burden is left entirely on the job seeker to find or create opportunities to plant pertinent information into the discussion, and make an impression. 

This can be very tricky.  With no structure or plan to the conversation, and no direct questions to address, it is difficult to bring focus to any particular strength or skill.

But the job is yours to lose, and you have this one and only opportunity to get a message across to this employer, so you have to act before time runs out.

There are a few things you can do to make the best of this interview and succeed at leaving the professional impression which you intended to deliver:

- Take charge of the discussion.  If the interviewer isn’t asking any question, you do the asking.  Bring up specific questions about the job and the responsibilities, then link the answers back to your own experiences.

- Make reference to things the employer has said, and segue to a pertinent point.  Say things like “to touch on what you were saying…” or “you bring up a good point…” followed up with an example of a related achievement you want to convey.

- Assert yourself.  Don’t wait to see where the interviewer goes next.  After 15 or twenty minutes of casual dialogue, the chances of this interview suddenly taking a more structured turn are pretty slim, and your time is running out.  Politely impose your agenda by stating things you really want him to know about you.

- Make it easy for him.  His interview style is probably indicative of his overall management style too, so extensive comprehensive training is not likely to form part of the initial job orientation. Demonstrate that you have done your homework and that you are a candidate who will require little in the way of training.  You will make a strong impression by showing how much you already know about the industry, the company, and the role.

As with any other style of interview, your preparation will dictate your success.  Do your homework, ask questions, and remain professional, and you should more than succeed at making a lasting impression.