Your best bet is to get sample by-laws from organizations in your state that are already 501(c)(3). That way you'll be sure they have the boiler plate pieces the IRS wants.
You never, ever want to write these from scratch. Look for groups with good, solid processes and use theirs as a starting point - customizing as needed for your group.
Aside from the obvious, like organization name, things that may be different for you are:
- Purpose
- Names/duties of officer position
- Who exactly is a member
- Whether or not dues are collected
- Officer terms, term limits
- Fiscal year
- Requirements on number or timing of general meetings and activities like nominations
Before you start writing the bylaws, you also probably want to figure out what type of organization you will be. If you plan to incorporate, your "organizing instrument" will be the articles of incorporation. If not you might have a constitution or articles of association, then the bylaws that define how your group operates. However, more and more groups (that aren't incorporated) are using a hybrid document that they call bylaws but actually has the basic organizational info (name, purpose, fiscal year, dissolution clause) PLUS the rules of operation.
The point is, you generally don't want to duplicate major sections. If you DO have two documents, put things one place or the other.