When I am sourcing new designers to work with I go to two places consistently. Dribble and my local coworking spaces.
Dribbble has thousands of submissions from designers around the world. It is easy to browse by category, review design and get in touch with a designer for your work.
Coworking spaces draw in talented business owners from all over your community. If you don’t have a designer at your local space, chances are the members there will know someone.