Adwords is a great tool for getting targeted traffic who will come to your website and buy what you are selling. But if you are not careful, adwords can also deplete your bank account and you may not have any sales to talk about. Usually, no one can get adwords right in the first go. Only with experimentation we can know which keywords perform well and which drives the revenue.
The biggest mistake that I see many adwords “experts” make is that they THINK if a keyword gets higher CTR and if the CPC is low, it is a good keyword. But they often fail to check if those keywords actually drive the conversions. Yes, adwords has conversion tracking facility and it can show you metrics like who landed on your landing page and may be converted into a lead, but it doesn’t show you if they converted into a buying customer later on. So the end conversion where the prospect has become your paying customer is the REAL conversion which has to be tracked.