During any job interview, never be afraid to ask questions. Two important questions to ask before you leave   the  interview are:

     1. "When do you expect to make a decision for this position?"
     2. "Is it alright if I contact you to find out what you decided?"

  First of all, by asking these questions, you show your  future employer  that you are interested in  the  position   and  that you posess a certain assertive quality.Second, you will have an idea of how long you will have to wait   to  find out if you have the job.Most  employers  will welcome  your  enthusiasm  and  let you  know a   certain   timeline  for their decision making process. i.e. "We will be having a staff meeting tomorrow afternoon to make   a decision and we should know by then." If you have a good idea of  when they  will make a  decision,  contact   the  person(s) that interviewed you either by phone or by email to know  whether  or  not  they  have  made a   decision.  if  they  have  not  yet  made their  decision,  contact   them  again  in a  few days.  Don't be  pushy!   Depending on the  type of Job you are applying for and department you are dealing with, judge  your  callback   timing accurately. If  you are applying for a sales job, then calling back every two days to know if you have the   job or not might be  seen as an aggressive quality they need for the position; I real go getter who just  will not   quit until he gets an  answer. However, if you are applying for the desk job in the accounting  department, you   might want to hold off  for a  week  or so  before  calling back.  You have to gage what is  appropriate  for  the   position you are applying for.

  Thanks and appreciation
  When you do call back or email the first time, do not forget to be courteous and polite. It is imperitive that you   thank your interviewer for the interview and the opportunity for meeting with them.