Try these search tips to get more matches:
Keep it simple
Use less specific (simpler, more generic) keywords eg bird instead of sparrow
Wildcards
Use the wildcard character * (asterisk) eg swim* matches swim, swimmer, swimming etc.
Booleans 1
Avoid using the terms AND and NOT, which restrict your search dramatically
Booleans 2
Use the term OR instead of spaces between keywords (each space is interpreted as an AND)
Quotes
Remove single quote marks around exact terms e.g. enter Eiffel Tower rather than 'Eiffel Tower'.
Singular
Try singular terms rather than plurals eg type flower instead of flowers