Analytics

Before you start sending traffic to your landing page make sure you have analytics in place. The standard is adding Google Analytics, you can also add Facebook Pixel and Linkedin Insight Tag depending on where you gonna run your ad campaign.

https://amplitude.com/ or https://mixpanel.com/ for user behaviour analysis

I would recommend installing session recording software so you can watch exactly what people do on the website and how they read/interact with information you put on landing page. Both of these services have free version so you can use for validation and later as well for free up to some point.

Session Recordings: HotJar/FullStory/Inspect

Tag Assistant and Facebook Pixel Helper, WASP.inspector https://segment.com/pricing/?ref=nav

UTM: UTM url Builder, Custom UTM, Remove UTM from URLs, Best Practices, BP From GO, BP From GO 2, BP 4, Template

GTM: Data Layer

Google Analytics: Basics of GA

Conversion tracking: Google AdsFacebook Ads Vid 2

Ad-Blockers: Avoiding Ad-Blockers 2