My initial thought is if you have to ask what questions to ask a prospect, you probably shouldn't be taking them on as a new client. However, everyone has to start somewhere. My advise...
1) Create a Client Profile interview template, print it, and take it with you.
2) Ask to have the decision maker(s) present at the meeting.
3) Have a goal at the end of the meeting. Network Assessment, project, etc.
The Client Profile should have the basics but think of what you will need to ask them in order to conduct a thorough assessment. ISP & Email service info, backup and disaster recovery plan, specialty programs to run the business, canned programs to run the business, age of hardware, do they have servers, do they have mobile users, smart phones, remote access, do they have any immediate issues, concerns, who has serviced their network previously, why are they looking for someone new, do they have county or state guidelines that have to be followed. You get the idea.
Our Client Profile template is 3 pages long and we take lots of notes, let them do all of the talking. Our main goal at the meeting is to get a paid network assessment. We provide them with a report of our findings, our recommendations as well as a recommended timeline for following through.
Good luck.
. Doing a job for the police etc make sure your insurance is up to date and you are a LLC/LTD company 
