For a small local cake business I found a few (fairly cheap) facebook ads worked really well. They gave my business a boost as well as word of mouth advertising from friends and family. I do still have a website with more photos and prices, as I don't believe you should be totally reliant on social media; after all, they could start charging or pull the plug at any time, and all would be lost! A combination works really well, especially for cancellations or last minute offers!