Far and away the best website to use is The LDS church's Family Search website. There you can search using the following topics for FREE:
 
• Census and Lists
• Court and Legal Records
• Cultural and Religious Groups
• Family Histories and Genealogies
• Key Genealogical Sites
• Land and Property
• Libraries
• Migration
• Military
• Places
• Record Keepers
• Research Support
• Royalty and Nobility
• Services and Tools
• Surname and Family Organizations
• Vital Records