Ask any Director or staff member to recite your Chamber's Mission Statement and you can safely bet on something close to an embarrassing silence. Since crafting it inevitably took countless hours of discussion to fine tune it's wording -- the theory being that it is important to state clearly exactly what you are all about -- then how come nobody knows what it is?
Yes, you may have a substitute slogan like "We're the voice of business" but that still prompts the question "How do you do that?" You need to be able to answer that question.
We expect newly-minted entrepreneurs to have prepared and practiced a powerful "elevator speech" ready to impress a potential investor. Exactly the same thing is true when asking someone to become a member of your Chamber of Commerce. You need to prepared and practiced. You need a powerful short story.
When your story outlines what you are doing and demonstrates your Chamber's commitent to your community then there's a high probability that your prospective member will be interested in learning more. You may still need the "stuff" in the membership package to close the deal but your chances are much, much higher if you have a story that you are proud to tell.
In addition, going through the exercise of writing your short story is an excellent way to remind everybody just exactly what you have been doing to improve the economic health and wellness of your community. It will be a win-win for all concerned.