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If your team is managing website analytics and constantly implementing new tracking requirements, you know that working with Google Tag Manager (GTM) often involves checking the same settings and data repeatedly. Are the required GA4 E-commerce data points in place? What about custom dimensions? To streamline this process and ensure a reliable setup, having a checklist is invaluable.
Based on a detailed checklist that outlines 75 crucial steps, this guide provides the core actions you should take before, during, and immediately after launching your GTM configuration. Following these steps can significantly improve the quality of your GTM implementation.
Phase 1: Planning and Structuring Your Setup
Before writing any code or setting up a single tag, proper planning lays the foundation for success.
Define Account and Container Structure:
Determine the ideal setup based on your client’s or company’s needs. If there are multiple websites, decide if they should share one container or be separated. Equally important is assigning the correct ownership and permissions to team members.
Prepare a Tag Implementation Plan:
Use a sheet to outline every tag you intend to publish. This structured planning allows you to foresee possible roadblocks and resolve them proactively.
Phase 2: Preparing the Website and Installation
The website itself needs certain technical adjustments to make tracking through GTM efficient.
Enhance Web Elements for Tracking:
- Add unique IDs to crucial web elements. This step makes interaction tracking much easier, as the Click ID and Form ID variables become reliable tools.
- Use the data- prefix for adding supplementary information to website elements (e.g., data-id=123). This data can then be easily retrieved using variables like the Auto-Event variable or the DOM Element variable in GTM. For example, if you need to track which e-commerce platform logo a visitor clicks, a developer could add a data-platform attribute to each logo.
Improve Form Tracking:
Ask your developers to make forms friendlier for GTM tracking. For instance, forms should only dispatch a valid submit event upon successful submission, not if there are errors. Alternatively, request that the developer fire a dataLayer.push event after a successful submission, which you can catch with a Custom Event Trigger.
Properly Install the GTM Snippet:
The GTM container snippet is split into two parts. The first part should be placed in the <head>, and the second part should be placed immediately after the opening <body> tag. Critically, never place the <noscript> part of the code in the website’s <head>.
Verify GTM Presence Across All Pages:
Use a web crawler (such as Screaming Frog) to check the entire website for the GTM container URL (https://www.googletagmanager.com/gtm.js) to ensure no pages are missing the required code.
Phase 3: Working with the Data Layer
The Data Layer is the mechanism that allows you to collect custom information from the website and pass it to GTM. It is vital that your development team understands its concept.
Data Layer Placement is Key:
If you need custom data to be available immediately on the ‘Pageview’ event, the Data Layer snippet must be positioned above the GTM container script.
Use the Recommended Syntax:
Avoid older syntax that uses a simple declaration (e.g., <script> dataLayer = [{ …. }]; </script>). If executed after the GTM container, this can overwrite the existing Data Layer object and break GTM. The recommended and more robust approach is to always use window.dataLayer.push. This ensures all snippets use window.dataLayer to prevent conflicts with locally scoped variables.
Preloading Valuable Data
The Data Layer should be preloaded with essential information.
User Data Examples:
- Is the user logged in? (Useful for creating custom triggers or Google Analytics custom dimensions).
- What is the Pricing plan/membership status (e.g., Free or Premium)?
- The User ID.
- The user’s Total spend on products/services.
- User preferences (like use of favorites or wishlists).
E-commerce Data (Crucial for Enhanced E-commerce Tracking):
- Transaction ID.
- Transaction Total (value) and Tax.
- Currency code.
- Product ID (or SKU), Product price, and Product quantity.
- Product category (using / as a delimiter for up to 5 levels of hierarchy, e.g., Apparel /Men/T-Shirts).
- Coupon code associated with the product.
Phase 4: Server-Side Tagging and Final Checks
For advanced setups, server-side tagging offers control and performance improvements, while final checks ensure deployment success.
Server-Side Tagging Requirements:
- Map a custom subdomain for your server-side GTM setup (e.g., at.yourdomain.com), and ensure it is not used by anything else.
- Update your Google Analytics tags to direct data to this custom subdomain, often using the server_container_url parameter.
Implement Deduplication:
If you use both client-side pixels and server-side tagging to send the same events to platforms like Facebook or TikTok, you must implement event IDs. The ad platform uses these matching IDs to deduplicate the data.
Check Privacy Compliance:
Ensure you implement a GDPR-compliant tracking consent mechanism and activate Consent Mode.
Final Verification:
Use the Preview and Debug mode to thoroughly verify your configuration before deployment. After deployment, check the console for any JavaScript errors using tools like TrackJS. If you are using external tracking scripts found online, always show them to your developers first to ensure they do not pose a risk to your website.
By systematically addressing these steps across planning, preparation, Data Layer implementation, and final checks, you can significantly enhance your GTM setup, moving toward a more efficient and robust tracking infrastructure.