All businesses and contracts start out with the best intentions, but a significant percentage of them are bound to fall apart. Prepare for it! Be clear with your partners about who owns what, who is responsible for what, and what mechanisms will be used to resolve disagreements should they arise.
Whatever you do, do not assume it won't happen to you, or that you'll figure it out when the time comes. Such assumptions are why more small businesses fail because of partner disagreements than just about anything else.
The same holds for contracts with vendors, customers, or anyone else. If you are in business, you will have problems. Lack of preparation for them is what keeps so many business attorneys in business.
Co-Founder and General Counsel