GA4 collects a lot by default: page views, sessions, scroll depth, outbound clicks. But the events that actually inform decisions (form submits, checkout steps, feature usage, plan upgrades) require custom implementation. Here are the 12 events every site should have firing before they look at a single report.
The 12 events that matter
For all sites
- form_submit: every lead form, contact form, newsletter signup
- cta_click: primary CTA buttons with a label parameter
- video_engagement: play, 25%, 50%, 75%, complete milestones
- file_download: PDFs, case studies, whitepapers
- outbound_click: clicks to external domains (including phone/email links)
For ecommerce
- view_item with full product parameters
- add_to_cart with value and item details
- begin_checkout with cart value
- purchase with full order data
For SaaS
- trial_start: with plan name parameter
- feature_used: with feature name parameter
- upgrade_intent: pricing page views, upgrade button clicks
Implementation via GTM
All 12 events can be implemented without touching your site code using Google Tag Manager. The general pattern is: Trigger → Tag → Preview → Publish.
For form submissions, use the Form Submission trigger type. Make sure "Wait for tags" and "Check validation" are enabled, otherwise otherwise GTM may fire before the form actually submits successfully.
Validating each event
Use GA4's DebugView (Admin → DebugView) with the GA4 Debugger Chrome extension enabled. Every event should show within seconds of firing. Check that:
- The event name matches exactly (GA4 is case-sensitive)
- All required parameters are present and have correct values
- The event fires once per action (not multiple times)
- Events are not firing on page load when they should fire on interaction
Marking events as conversions
Once validated, mark your key events as conversions in GA4 Admin → Events. GA4 supports up to 30 conversion events. Prioritise: purchase, form_submit (lead forms), trial_start, and upgrade_intent.
Import these conversions into Google Ads for smart bidding. This is often the single highest-leverage action an advertiser can take. Google's smart bidding is only as good as the conversion signal you give it.