Advice from an old farmer: Avoid signing anything.
I just started saying, "If you are in need of my services, and require me to sign an NDA, you must cover the legal fees necessary for my choice of lawyer to review it."
Depending on where you're from, being aware of your local intellectual property laws and the like should not take too much effort in my opinion. Whenever I receive an offer/a contract/etc I take a lot of red pen to it and send it back with my comments. Most companies have no problem with this, the ones that do are good to avoid anyway.
I've had some success with, "Okay, well what can we talk about without the NDA?"
NDAs are hard; there are good reasons for them, but they are too-easily proffered and too-often signed.
Where possible, they are far more humane if they have a reasonable end-date.
At the end of the day, these agreements (and non-competes/non-poaching clauses), among well-intentioned people, can boil down to the spirit of Stuart Freedman's request [1] that Gerry Garvey memorialize an oath: "I swear that I will not screw you unnecessarily."
These agreements, however, are a bulwark against the ill-intentioned and malevolent.