Any author or blogger should protect his work from being copied, shared or stolen. You should get legal advice on topics such as: Copyright issues, Non-Disclosure Agreements (required when working with contractors ), JV Partnership (required when co-authoring books), Consignment Agreements (required when you contact bookshops.)
Tip #1: Laws vary by country, province and state. Therefore, it is best to contact a legal professional in your area.
Tip #2: Always sign a Non-Disclosure Agreements when working with other freelancers.
Tip #3: Read the The Ultimate Guide to Copyright Web Site