From FamilySearch Wiki
Tips for Searching an Index
Top 5 Tips for Searching Indexes
| Exact Spelling
|| Some online indexes require exact spelling to get a result. Try different ways of spelling the person's first or last name.
| Use Less Info
|| If you did not get results, type in less information about the person. Try searching only for the first and last name of the person.
| Add Info
|| If you have too many hits, try adding information including approximate birth date and the county
| Try Another Index
|| Different indexes use different search parameters and your ancestor may be located in one but not the other.
| Incomplete index
|| Some online indexes do not include all counties for all years. Your person's birth record may exist but not in the index you are searching.Check all possible indexes available.|
Tips for Searching Beyond the Index
The birth of your ancestor may not have been recorded official by county or state agencies. Use other records to find birth information.