Businesses do not really start with a good idea. Not even with great ideas. After all, ask any common man and he's likely to have several good ideas. But ideas are just that. And besides, many people can come up with the same idea anyway. What's more, if we're to believe the gossip (?) in IT, Microsoft wasn't Bill Gates' idea... it was somebody else's (or was it internet?).
Anyway, the point is ideas are just that, ideas. What matters is what you do with an idea, be it your own or the neighbor's.
So, to start your own business, you have to do your market research first. It doesn't even have to be anything fancy and exhaustive. Some even have started businesses that just came to them after realizing what isn't being made available in the neighborhood. And that's where you can start your research. You can either sound off your ideas with friends and family, or ask acquaintances for some leading questions.
Of course, you can also google a lot of things nowadays, and maybe even check for patents. But usually, you can do with just asking the right questions from the right people.
And even after you've started your business already, be it a soft opening or already a full-scale launch, it wouldn't hurt to continue asking for feedback and more ideas. Always, the biggest room in the house (and in any business) is the room for improvement. take care to occupy it and maximize it.