Most GA4 properties we inherit were created in about four minutes: someone pasted the tag, saw real-time data appear, and moved on. The data collects, the reports populate, and everything looks fine until somebody asks a question the setup was never configured to answer.
This guide covers the setup in the order it should actually be done.
1. Start with a measurement plan, not a property
Before you create anything, write down the actions on your site that indicate commercial progress. For a B2B site that is usually a demo request, a contact form, a pricing page visit and a document download. For e-commerce it is the standard purchase funnel plus whatever is specific to your catalogue.
The point of writing this down first is that it becomes your definition of done. Without it, GA4 setup has no finish line and you end up tracking whatever was easy.
2. Create the property and data stream
Set the reporting time zone and currency to match how your business reports, not where your agency sits. These cannot be changed retroactively, and mismatched currency is a common cause of revenue numbers that never reconcile with finance.
In the web data stream, review the Enhanced Measurement toggles individually. The defaults collect scrolls, outbound clicks, site search, video engagement and file downloads. Most are useful. Site search will produce nothing unless your search parameter is configured, and the default scroll event only fires at 90% depth, which is rarely the threshold you actually care about.
3. Configure events deliberately
GA4 has three kinds of events worth distinguishing:
- Automatically collected — page views, first visit, session start. Nothing to do.
- Enhanced measurement — the toggles above.
- Custom events — everything specific to your business, which is where the real work lives.
Send custom events through Google Tag Manager rather than hard-coding them. It keeps implementation in one place and means marketing can add tracking without a deployment.
Name events consistently and in lower snake case: generate_lead, demo_request, brochure_download. GA4 event names are case sensitive, and a property with both Demo_Request and demo_request will quietly split your data in two.
4. Mark conversions carefully
Marking an event as a conversion is a single toggle, which is exactly why it gets over-used. Every conversion you declare becomes a signal that ad platforms may optimise toward, so a newsletter signup marked as a conversion can pull an entire Google Ads campaign toward low-value traffic.
Mark only the events that represent genuine commercial intent. Track everything else as a normal event and report on it separately.
5. Add custom dimensions before you need them
GA4 will not retroactively process event parameters you have not registered as custom dimensions. If you are sending a form_name or plan_type parameter, register it as a custom dimension on day one, or you will have months of data you cannot break down.
6. Set data retention to 14 months
GA4 defaults to two months of user-level data retention, which quietly cripples year-on-year exploration reports. Change it to 14 months immediately. It is free, it is one setting, and almost nobody does it.
7. Filter internal traffic
Define internal traffic by IP in the data stream settings, then activate the filter. Left undone, your own team, your developers and your agency all appear in the data, and on a low-traffic B2B site that can be a meaningful share of sessions.
8. Link the platforms that matter
Link Google Ads, Search Console and BigQuery if you have the volume to justify it. The Google Ads link is the one that matters most: without it, conversions cannot flow to bidding, and GA4 cannot show you paid performance in context.
The settings people most often miss
- Data retention left at two months
- Custom dimensions never registered
- Internal traffic never filtered
- Cross-domain measurement not configured on sites with a separate booking or checkout domain
- Unwanted referrals not excluded, so payment gateways appear as a traffic source
- Too many events marked as conversions
Where to go from here
A correct GA4 setup is mostly discipline rather than difficulty: decide what matters, name it consistently, and configure the handful of settings that cannot be fixed retroactively. If you want a second pair of eyes on your setup, our analytics and tracking team runs a free tracking audit that covers GA4, Google Tag Manager, conversion events, CRM integration and attribution.