The short answer
Tracking breaks quietly. An event renamed in one release, a tag that stops firing on Safari, a purchase counted twice: each one makes later decisions worse, and nobody notices until a test result makes no sense.
A tracking plan prevents that. It’s one shared table of every event, why it exists and whether it’s been tested. Copy our tracking plan template to start.
Five rules for event tracking
1. Start from questions, not clicks
“Track everything” produces thousands of events and no answers. Start from the questions in your measurement brief: where do shoppers drop out of checkout? Each question needs specific events. Anything that doesn’t answer a question can wait.
2. One naming convention
Pick one style and use it everywhere:
- lowercase with underscores:
plan_select, notPlanSelectorPlan Selected - consistent word order (for example, object then action)
- no variation names, page names or dates inside event names; put those in parameters
Use your tool’s recommended names first, such as GA4’s add_to_cart, begin_checkout and purchase (Google Analytics Help).
3. Parameters carry the detail
One form_submit event with a form_id parameter beats twenty events called contact_form_submit, demo_form_submit and so on. Define each parameter’s allowed values in the plan.
4. No personal data
Never send names, email addresses, phone numbers or free text from forms to analytics tools. Watch for personal data hiding in URLs (for example ?email=) and page titles.
5. QA before trust
An event isn’t “done” when it’s built, only when it’s verified:
- Fires once per action, on desktop and mobile, in the main browsers
- Fires identically in every variation of a running test
- Parameter values are correct in debug view
- Counts roughly match the backend for a week
Broken or uneven tracking is one of the common causes of misleading experiment results, including sample ratio mismatch (Kohavi, Tang and Xu, 2020).
Keeping the plan true
- One owner per event who’s told before releases that might affect it.
- Review quarterly: remove dead events, re-verify the important ones.
- Change log: when an event changes meaning, note the date, so nobody compares before and after without knowing.
What to do next
Copy the tracking plan template, fill in your funnel events, and set them up in GA4 with the GA4 for CRO guide.