i used to just drop the keywords in get the results but i noticed lately that there are more options (Broad Match - Phrase Match - Exact Match Negative Keyword) which one im suppose to use for keyword research purpose not for using adwords as an advertiser !
You should use phrase match or exact match If you try to research the phrase used cars, Broad match will return all searches that included the two words used and cars in any possible way in the search term. Phrase match will return all searches that included the two words used and cars in that order, i.e "used cars". Exact match will return only searches for "used cars". Not "used cars Los Angeles", but only "used cars".