Ideally, some "writing guidelines" would help. Not knowing how, or what to contribute is usually the main hold up. For example, confusion about the kinds of suggestions which would even be remotely possible to implement from a coding standpoint. And/or somewhere where it's easy to see what other topics have been previously discussed usually helps a lot. Heck, even just some instructions for things that are and are not acceptable content/tone/themes.
Or at least that's my experience/perspective in regards to hang-ups about suggestions.