While these books specifically address taxes, they are good reading:
SELF–EMPLOYED TAX SOLUTIONS BY JUNE WALKER -
Walker’s book is an easy–to–read and understand guide to money saving and audit–proof tax and recordkeeping for independent professionals.
SMALL BUSINESS TAXES MADE EASY BY EVA ROSENBERG -
Written by an Enrolled Agent licensed by the IRS and known as “TaxMama,” Rosenberg’s book covers tips and guidelines to cut your tax bill and gain the greatest possible advantage out of each IRS rule and regulation.
Also, your state's website usually has good info on the business entities it allows. Google your state's secretary of state's office and then go to "corporations" or "business organizations."
For example: I just did this for Texas and found this great page on how to select a business structure.
http://www.sos.state.tx.us/corp/businessstructure.shtml
Many other states have done this. Also, I have prepared a similar chart on the pros and cons of the different business structures and will send it to anyone who emails their mailing (snail mail) address to me at carolyn(at)photoattorney.com
After you do your research, be sure to talk with your accountant and/or your attorney about what business structure will work best for you.
Best,
Carolyn