Don't bother to hide your ideas. Ideas themselves are useless unless executed appropriately with strong business model. And people wont steal your idea unless they are sure that there is enough market traction. If your idea is really that great, you are sure to attract enough competition sooner or later. If your idea is built on thin ice which can be easily copied, then there is no point wasting your time. You can use that as a base and build entry barriers around that which will make you a strong player.