As I'm growing my business, a lot of people tell me that I should hire a director of business development, but I'm not sure what I should be looking for.
As others have mentioned Business Development is a very broad term and can be what ever you want just like the last line of most corporate job descriptions...."All other assigned duties"
Depending on the size of your company and at what stage you are in will determine the best solution. Of course that is not within your question but I will assume you are profitable and right on the cusp of taking off.
One idea is to identify your target market and who those customers/partners should be and then do a search for an individual that has experience with those types of customers or even better has specific relationship with those vendors from previous or current roles they were in.
Sometimes business development is hiring someone that can open doors to larger opportunities that can really drive the marketing, branding and awareness to your product/service/business.