How i determine Profitable PPC ad campaigns

evryone might have different results, but what i do is to run small ad for starting $10 or $5 to see how it perfoms, then when you see perfomance, now this way yu have found a perfect campaign to do which will be good to repeat again and again many ads platforms when you are using them, i create different ad units first and then determine which works more than others and then i delete the one not having good results and remain with ones with good results