1. When searching online databases less is always more. Enter as few details as possible, perhaps using the surname or forename. Try different combinations of name, age & birthplace.
2. Use wildcards. * stands for any number of characters (including no Characters) ? stands for a single character.
3. Avoid precise birthplaces where possible. People were not always consistent when it came to stating where they were born. People tend to be less precise the further they are from their birthplace.
4. Consider alternative spellings. Standardised spelling of personal & place names is a relatively modern concept, so Brown and Browne can be the same name!