When searching for records, ask yourself: Who cares? What agency, municipality, or person cares enough about the information you're looking for to keep and organize it? Courts? Historical societies? At the local or national level? This will help you zero in better on a starting point.
Search for multiple spellings of names. Some collections may use the "Soundex" system, which brings together differently spelled names that sound the same. See the National Archives' explanation of Soundex.
Other Places/People to Contact
If you know which state you need your information from, try consulting this list of state libraries and archives, and seeing what records they have available.
If you have a city or county in mind, try Googling that city or county with the words "archives" or "public records" to find a local agency.
Consult a list of "Repositories of Primary Sources" all over the globe (from the University of Idaho).
Also check out "Archives Made Easy," a curated collection of archives by country from the London School of Economics.
The library also owns a reference book called The Genealogist's Address Book, which can help you identify other local and nationality-specific sources.
Suggest a source!
Have you found a great genealogical source? Submit it here and have it added to the guide.