The problem there is that those who are involved in web and graphic design groups are generally your competitors, not your prospects. Instead, look for the markets you target with your business and join those groups. For instance, one developer I know targets industrial markets... cars, construction, heavy equipment, etc. If you want to get your business off to a good start, look for a market that interests you and join some of those groups. It will be easy to become a visible and active member, which is what it takes to get your business (and social media following) moving.