AND - use this when ALL the words must be in your results. This will narrow your results. Example: apples AND oranges; peanut butter AND jelly
OR - use this to connect synonyms, when ANY can come back in your results. This will broaden a search. Example: women OR woman OR girl; cat OR kitty OR kitten
NOT - use with caution since this will eliminate results with the specified word.
You can utilize Google's Advanced Search to help narrow your results from the start:
The domain name of a site can give you a good idea of what content you might find there: