Make sure you know the location of the interview (e.g. if the employer has more than one office) there would be nothing worse than turning up late!
If you are going to be late, let the agency know straight away. Don’t call the company unless the recruitment consultant has given you permission to call the client.
If you are using public transport and have an iPhone or other smart phone, pre-set Google maps so you can easily find the location.
If you are driving then pre-set your satellite navigation so you are not stressing on the day!
It’s a good idea to arrive 10 minutes early for the interview to give yourself time to gather your thoughts and to be calm before meeting the interviewer.