I would tell the beginner version of myself to stop assuming. Ask the client more questions, understand the business more before you start anything. You NEED to be on the same page.

Biggest mistakes I see daily (freelancer in digital marketing) are exactly what you said, no GTM, no analytics, no data. Stabbing in the dark doesn’t work, and if it does you waste a lot of money getting there.

Conversion tracking should be setup BEFORE any advertising starts, unless you are like Pepsi and want to spend millions on ‘awareness’, then it’s less important.

What you put in is what you get out with PPC, in my opinion.

If you want to be more specific, let me know 🙂