How do I set up GA4?

GA4 replaced Universal Analytics in July 2023, so if you are starting fresh in 2026 there is only one version to learn. The setup itself is not hard, but a sloppy install is worse than no install: you end up making budget decisions on numbers that do not reflect reality. The goal of a good setup is simple. Every meaningful action on your site (a lead form, a sign-up, a purchase) should fire a clean event, and the events that matter to revenue should be marked as key events so you can see and optimize them.

Start at the account level. A GA4 account can hold multiple properties, and each property holds data streams. For most businesses you want one property per brand or domain, with a single web data stream for your site. If you also run an app, you add a separate stream for it and GA4 stitches the sessions together. When you create the web stream, GA4 gives you a Measurement ID that looks like G-XXXXXXX. That ID is what the tracking tag uses to send data to the right place.

Install the tag through Google Tag Manager rather than pasting code into your theme. GTM gives you a clean separation between your site and your tracking, so you can add, edit, and debug tags without touching developer code every time. Create a GA4 Configuration tag in GTM, drop in your Measurement ID, set it to fire on All Pages, and publish. Use GTM Preview mode and the GA4 DebugView to confirm page_view events arrive before you trust a single number.

Enhanced measurement is on by default and automatically tracks scrolls, outbound clicks, site search, and file downloads. That is convenient, but it is not the same as conversion tracking. The actions that drive your business (a quote request, a demo booking, a checkout) need their own events, either configured in GTM or sent from your site. Once those events exist, open Admin and mark the important ones as key events. Only key events feed Google Ads bidding and show up cleanly in your conversion reporting.

For DACH and EU sites, Consent Mode v2 is not optional. Without it, GA4 either loses consented data or collects data it should not, and Google Ads loses signal for bidding. Wire your consent banner to Google's consent signals so tags adjust behavior based on what the user agreed to. This keeps you DSGVO-compliant while still recovering modeled conversions from users who declined cookies. Get this wrong and your numbers and your legal exposure both suffer.

Once events and consent are clean, link GA4 to Google Ads under Admin. The link lets you import GA4 key events as Google Ads conversions and build remarketing audiences from GA4 segments. The deeper work (ecommerce items, purchase value, refunds, server-side tagging) is where most measurement mistakes hide. If your store needs item-level revenue and ROAS, follow the detailed ecommerce setup before you rely on the data.