I am very excited but also very nervous as well. I have my first oral board interview with a large police department on the 21st! I plan to study to county more, read the mission statement and look at the crime statistics to know more information about the county than I do now.

Any other suggestions besides wear a suit and shave?

Be confident and use common sense. Don't over think it.

That's great advice. I've been through three oral interviews-2 police depts. and the federal agency that hired me. One of the depts. was a small city and they were very casual and laid back. The other dept. was a medium sized city that was composed of 4 officers and a guy wearing a white smock. Two of the officers tried baiting me to get me to break down, which I didn't. One was wearing his motorcycle uniform complete with helmet on the table. His only question for me was "Do you like taking orders? I'm going to have you cleaning out patrol cars. Are you going to like that? Well, are you?" This just seemed unprofessional to me and I wasn't disappointed to hear I didn't get the job. The federal agency oral interview board was a lot more professional and only dealt with legitimate questions and included several scenarios that they read from a book.

Be cool and as mentioned, use common sense. Good luck.

Be able to articulate your answers without using slang terminology. Suit and shave sound good, make sure shoes are shined. Look the interviewers straight in the eyes, don't look up or down, it looks like you're guessing then. If you don't know the answer to the question, say so, don't BS. Sit up straight if allowed to sit down. No slouching or crossed legs/arms. If you don't understand the question, ask for a clarification. 
I've sat on many, many oral boards in my career. And conducted quite a few. 

When you answer the scenario type questions (what would you do if?.....), have a definite answer, not "I think I would...." or "I'd probably......."

Went through boards in Sept. and posted here asking for advice as well. Here's the thread, lots of good info that helped me.

Thanks for the tips every one! I have been reading up on the county and their crime as of late but will be hitting it hard today and tonight as well as reading the mission statement and looking at senior command.