You might want to follow up the interview with an email to the employer thanking them for the opportunity, to clarify an aspect you are uncertain of or send them something they requested such as a work test, certificate etc.
You might feel quite tired after an interview, as the build up might have been quite tense or taxing and then thinking on your feet of all the responses is tiring. If you can relax afterwards that would be most beneficial. You may feel elated the interview is over and want to celebrate your achievement with a treat or something that you enjoy.
It could be helpful at some point after the interview to reflect and evaluate your performance. Try not to be hard on yourself – use it as an opportunity to work on and strengthen your answers for your next interview. Focus on your strengths, what answers did you excel at? Were there any questions or aspects you found hard? Could you build on those and enhance your response?
Waiting to hear the outcome of the interview can be really stressful. Hopefully they would have informed you of the time a decision will be reached but if not you could ask them either in the interview or afterwards.
If you have the energy and motivation then you could continue job searching and applying just in case another candidate is selected. This is a great way of increasing your chances and honing your skills. New opportunities emerge and if you are unsuccessful on this occasion but have made other applications it will help you to focus on being proactive, as opposed to feeling a sense of failure or hopelessness.