1. dress nice. Men should wear a suit or slacks, dress shirt and a tie. Women should wear a nice pair of slacks or skirt with a nice top (nothing see-thru or low cut). Make sure its clean and ironed. Navy blue or black with a light or neutral shirt is always safe and professional looking. Remember you are working for the police department and you need to make a good impression. When I showed up for my interview, there were 2 men wearing jeans (one with a tshirt and another with a dress shirt) and a woman wearing a tight above the knee skirt with a nice blouse that was showing a bit too much cleavage. None of those people got the job. You can give them the best answers but if you're attire is sloppy or too revealing, chances are good you won't be getting a callback.
2. If you can arrange it, do a sit in at the 911 call center and/or arrange a ride along with the police department to get to know the area, to talk with personnel who can give you information on what the job is about. Sometimes the interviewers will ask "What have you done to prepare yourself for this job?" and telling them you've done one or both will impress them. It'll show them you truly want the job and you're making an effort.
3. If you can't (as some agencies will not allow it), then research the department online. Read their mission statement, find out the areas they cover as well as the surrounding areas so you know what outside agencies you may have to work with. A common question is "Why do you want to work for our agency? What do you know about our department?"
4. Check out www.911dispatch.com/jobs/job_interview.html It will give you common public safety dispatch interview questions and a hint on how to answer the question. If you need more hints on how to answer a question, just google common interview questions and answers......Good luck