Appearance is invariably the first step. I know it sounds trite (and even inflammatory to some) but it is a fact of life; most officials are too tactful to say it --- so I will:
"If you don't look like us, if you don't talk like us, if you you don't act like us, and if you don't perform like us --- you are not one of us. Thou shalt not pass."
Some may call this a hard line approach. We call it a real world, practical approach. Once you let your employees (paid and volunteer) know what is the mission and standards of performance, service, appearance, behavior, etc., they know exactly where they stand and what is expected. This should be carefully crafted and stated right up front before anyone is hired or signed on. It saves a lot of grief down the line. I have seen all too often government managers report that their volunteer program(s) failed. In analyzing the reasons, the most common is their reluctance to state up front and in writing what are the expectations of the government (or business, etc.).