in writting ads that attract costumer, choosing the rightful keywords play some enssential role. there are some tips for choosing a keyword. 1. use keywords b/w 2-3 words. 2. use Negative keywords. like expressing any offers. words such as discount, cheap, organic etc before a keyword. for example if your keyword happens to be ballet shoe, negative keyword expression for Discount, will be "Discount ballet shoe, or cheap shoe etc. 3. Use the keyword tools.