I can actually answer this. The idea that started my company way back in the 1990s was an ok idea, but it was not fantastic. What was fantastic about it was it had a magic balance between complexity and intuitiveness. What happened when I told people about it is was the first 30 minutes they sat there totally confused, but at some point around the 30 to 45 minute mark they would have an eureka moment where everything would fall into place and they would get it. The effect of this was truely amazing - basically people would come to believe that they had thought of it themselves and of course at that point selling was not a problem - people literally gave me large amounts of money for free because of this effect.
I should mention that while I have had much better ideas since (as well as lots of worse ones), none have ever had that magic quality. All I can say is look for ideas that allow people to discover the eureka moment themselves after 30 minutes. Once you have this you almost can't fail to raise money.
I wanted to avoid going into details as it is unlikely to be of interest to anyone here, but the actual idea eventually ended up as U.S. patent 6,737,253 [1].
I see. Well, that is not my area of expertise, but it sounds interesting, even if I don't understand it. So you turned that idea into a product or service, and made a business of it? Did you sell it for research or forensic or medical or...? Sounds like a good story, though maybe one you'd have to be in the field to understand the details of.
I actually sold it twice to two different companies. The first time was when it was just an idea and when they passed on it (but after they had given me enough money to prove it) I sold it to the second company for 100x more. At no point did I ever have to give up any equity.
The rather ironic thing is I actually came up with a much better idea [1] to solve the same problem, but I was never able to make any money from it. I am far more proud of the later idea, but it did not have the same magic.
I should mention that while I have had much better ideas since (as well as lots of worse ones), none have ever had that magic quality. All I can say is look for ideas that allow people to discover the eureka moment themselves after 30 minutes. Once you have this you almost can't fail to raise money.