Well, keywords are the terms which can explain your services Or products and you have to bid on those keywords by looking at their competition, search volume so that you can get the decent reslts. There are so many tools which you can use in order to get the best keywords for your PPC campaign like: Google keywords tool Spyfu.com Semrush.com Thanks asim_farooq633 (Skype) Asim
Take the optimized suitable keyword with high search volume and low computation and find KEI (keyword effective index) for better results.