You can communicate allot to people before you bring them on board without disclosing while establishing sufficient mutual understanding to make the right decisions.

If you are a programmer, use the same mental models you use to explain your work to less experienced peers. Metaphors left and right.

What you don't want to do is tell them business direction, revenue models, any leads you might have, with who and their nature, and anything else that might be used to screw you over.

You can keep your secrets really well, as long as you're not soliciting VC money or cofounders. If you intend to pay people, even if deferred, you can look them in the eye, tell them what you did before and you will find plenty of people who will have faith in you.

I also found it really helpful not disclose the name/website of the company to anyone you're speaking with directly. Aside from all the obvious reasons why not, you could also come into contact with a chatty social non-business blogger-type person who will running his mouth.