Test your idea. Decide who your key market will be (ie who will purchase your product or service?) There’s no point creating a business if you have no customers! So go out and see if you can find them.
Ask youself: what type of person fits the bill? Women, men, teens, kids? What age are they? Where do they live? Are they single or do they live with partners? Are you better off selling your product or service to another business (this is called Business to Business sales)?
Once you’ve decided on your customer, go out and find a few. Ask them what they think of your idea. Is your product or service something they would pay for? If the majority say no, listen to their objections and decide if they are valid. If you think they are, adapt your idea, or try a new one.