if you are not successful
advice for improvement
An unsuccessful interview is not the end of the world; capitalise on your experience to improve your presentation and your responses. The interview will have given you an opportunity to discover the company's corporate culture, a job/position, as well as questions from recruiters which you could well be asked in future interviews.
In a constructive manner, ask the recruitment officer or the manager, if you met him/her, to explain the reasons why you were unsuccessful. It will enable you to take stock of your interview and better prepare for the next one.