Besides the common responses like pick an idea you actually want to work on and will enjoy doing and where you have the skills to do the work needed...

I recommend doing some research into how large companies vet new product ideas and borrowing some concepts from that. I realize MBA-type practices taught in business schools get a bad rap from many folks and frankly a lot of the bad reputation of MBAs is deserved. But there are tools and procedures for how bigger companies decide whether to start a new product line and these are worth learning about. For example, how does Apple decide to launch the iPad or how did they decide to launch the Apple Watch? And how does Apple decide to cancel/not launch the dozens of other internal product ideas they have that don't see the light of day?... Testing the idea, it's market potential and digging into the overall pros and cons and risks of an idea, all have known steps and processes that can work at a startup-level idea too. Nothing is 100% for sure a good idea or bad idea - Plus you don't have to listen to the results of your product vetting, you can launch an idea with low support for it or decide not to launch an idea that has tons of potential, either way I think it's worth taking the time to understand these factors.

I heard something on the Tim Ferris podcast the other day about how Kevin Kelly (founder of Wired) tries to give away or kill as many of his ideas as possible. If no one takes the idea or he can't kill the idea with a fatal flaw, he knows that he needs to work on that particular idea. That said, ideas are a dime a dozen while execution is priceless.

Talking to myself here as much as to you.

For regular business, i.e., I need to make a living and I'm not looking for VC to build a unicorn, it's usually "do I have a paying client lined up?" Most service businesses are like this.

I would say everyone hashes out new ideas. Implementing them and selecting profitable ones is the difficulty. I will echo most points made by people here.

Solve a problem or a need, that is the idea that will work

Lowest effort (both technical and marketing) for highest return (a real and approachable market). Many times the effort would be too much for negligible return, so move on.

If a lot of people tell you - "I'd definitely want that". Build it. Ideas don't exist anymore.

Just ask people for their requirements, that'll be your idea.

I don't. I've had thousands of ideas, and implemented none.

I think my ideas are too ambitious. I can no longer go back to limited and realistic ideas.