Consider goals at a granular level, such as top-line business goals or marketing objectives. You can then work backwards to determine how PPC will impact the organization. Find out how many leads, sales, impressions, visits, or other key metrics you should measure.
The worst mistake I am seeing people doing in PPC, is creating their landing pages and advertising campaigns as per how they desire, without any regards for the policies of the respective advertising platform for example Google Ads, etc.
Example, keywords are about potatoes, ad headlines about fish, ad description about swimming and landing page about tables.
The algorithms of various advertising platforms such as Google Ads, Facebook Ads Microsoft Bing Ads, are nowadays quite pretty beefed up, so one has to be super careful nowadays.