Do folks have experiences to share on validating the idea without giving it away? Isn't there a risk that the if you tell people one of them will take your idea and run with it?
"Don't worry about people stealing an idea. If it's original, you will have to ram it down their throats." -- Howard H. Aiken
I think it's a legitimate worry, but a small one. Novice entrepreneurs overvalue ideas. The majority of startups make major changes along the way. E.g., PayPal was, what, Levchin and Thiel's fifth product?
And the real magic to PayPal wasn't money transfer; it was the loss prevention that kept the business viable. The thing that distinguishes successful entrepreneurs isn't that they all had one good idea 5 years ago. It's that they kept having new ideas, and had the drive to push their ideas out into the world so that they could learn enough to spark the new ideas.
Practically, there may be a very small number of people who a) are smart and experienced enough to appreciate your idea, b) have more resources to execute, and c) aren't busy doing something they like better. Try not to let those people understand the secret sauce. But those people are hopefully not your customers, who are the main ones you should be validating your idea with.
You test your idea on actual customers, you don't tell your idea to HackerNews. And even awesome companies like Facebook screw up when they test by running bad tests. Example: Home. Facebook tested Home on employees who usually use iPhones. Oops. If any of them read Robert Scoble or talked to a single Android fanboy, they'd realize Android is about customization. If a Nexus fanboy likes the Sulia widget or whatever you call it, said fanboy is not going to want to use Home when Home displaces Sulia.
