Are you looking for an unpaid intern? Because you will get what you paid for. If you are just starting out, determine how important your social media strategy is. If you can afford to do so, you should allocate some funds to it.
Post some initial social media job openings on sites such as peopleperhour.com and elance.com. This way you can review people's portfolio and get an idea of their skillset. People experienced with social marketing are very prominent on these sites.
But here's the secret:
Say your long term budget is $100/mo a week for social media marketing. Expect to spend $300 your first week. Why? Hire three people on these sites to do the same job. Then have them execute. Choose the person who had the best deliverables and keep them long term. Obviously tweak your spend based on your available budget.
Don't be afraid to take on someone that is not local. Some of the best people are on the other side of the world. Just be sure you have the ability to manage them appropriately.