If you are not a committee member responsible for a report, or have not been asked by the Board to address something during new or old business, then Open Forum is the place to
Typically people are asked to keep their remarks to a 5 minute maximum, and to submit their ideas in writing. Nooooo, you don't have to have a whole term paper written up, but it's really better to have at least an outline of your points in writing so you don't get misquoted in the minutes. Also, sign your statement(s), and have those people you say support it sign it, too.
Be aware that bringing up an idea is a presentation--not an agenda item. The Board can't drop the rest of the meeting's agenda and discuss or vote on your new idea that night. And if you are speaking about an item to come on the agenda later that evening, your remarks will be considered then. Or you might be hooked up with a committee that's addressing your idea/concern on a different day (as well as going on record during Open Forum.)
Individual Board members are sometimes approached outside of meetings about 'controversial' issues with a verbal, "The Co-op should _____!"; many times followed by, "but keep my name out of it." Your idea really only holds weight when it isn't 'whispered down the lane'. An individual Board Member has no authority--the way to really be heard is to show up at the beginning of a Regular Board Meeting and address the full Board. You can also email your signed, open forum remarks to for the Secretary to read during Open Forum.
Your fellow Co-op Member,
Patrice