Google Analytics free version comes with 20 custom dimensions and 20 custom metrics. So often I see these not being used at all. GA360 comes with 200 custom dimensions and metrics, and some say who would use that many. I thought I would list out some handy custom dimensions you can implement.

The first few are general ones that people have talked about often. Here are some other articles that mention it:

https://www.simoahava.com/analytics/13-useful-custom-dimensions-for-google-analytics/ 

https://medium.com/compassred-data-blog/how-to-setup-a-custom-task-to-capture-client-id-session-id-and-hit-id-tracking-using-google-tag-580543e2eda7

I recommend

1. Session ID - Session Scope

2. Client id - user scoped

3. User ID - Session scope

4. Hit Timestamp - hit scope

5. Hit type - hit scope

6. Full referrer - hit scope

7. GTM Container ID - hit scope

8. Payload count - hit scope

9.  Redirect Count - hit scope

10. Navigation Type. - hit scope

11. Tab Type - hit scope

12. Tab ID - hit scope

13. Tabs Open - hit scope

Thanks so much to Simo Ahava for setting these out. These are great on any website, content or conversion based. 

User Dimensions

14. User ID - hit scope

I found it handy to have it both as user scoped and user scope to see if this changes over time. 

15. Logged in Status - hit scope

Storing the if the user is logged in at each hit helps to know when in the funnel users log in, useful for eCommerce sites where they are prompted to log in as they checkout.

16. Postcode - user scope

If through a form or checkout a user enters a postcode, storing this will help with personalisation, as GA only allows you to get down to city level. This is not seen as PII in Australia but would check how specific postcodes are in your country and if allowed. 

17. Closest store/branch - user scope

If your organisation has physical stores as well as an online presence you may want to personalize or report against their store, especially when it comes to stock levels. This can be stored when a users postcode is entered with some development from the back end.

Search Dimensions and metrics

Though there are some details in Google Analytics on search it has its limits, like searches with zero results or what results people are clicking on.

18. Search Term - hit scope

Though stored in a separate dimension it has it’s limitations and to combine it with the following dimensions is hard, so best to store it in your own.

19. Search Result - hit scope

Which result was clicked, combined with what the search term was it can show more about your user behaviour?

20. Filters/Facets - hit scope

If your search has filters, such as price range, colour, brand, style, these can be saved to know what types of content or product people are looking for in regards to search terms

21. (now you need GA360) Search category - hit scope

Though you can send the category with the query as an inbuilt dimension but what about using machine learning to guess the category they are searching for. Cloud functions and AI tools can use NLP methods to group your searches into categories, e.g. if you are a government site - marriage, health, recreation activities

Custom Metric 1 - Number of Search Results Returned - hit based

Custom metrics don’t get used that often but this one is handy. For each search, store how many results are returned. This lets you know if people are searching broad or narrow and more important items people 

Product and eCommerce Dimensions and metrics

Once you have products set up there are a few attributes that you can set along with name and id, GA comes with brand, category, affiliate, variant, but here are some others:

22. Sale Flag - product scope
Is the product on sale or not, is it listed as a best seller, 50% off or 2 for 1. 

23. Stock status - product scope
Is the product limited stock, out of stock, in-store only - or even have the stock level at each point.

24. Release date - product scope
Or this could be days since release date - are people buying older products or do people only buy them when they are first released and then drop off.

25. Product review score - product scope
Does the review score impact if people buy it? It is assumed that people buy things with a higher rating but now you can have the actual data to prove if it is true.

26. Delivery availability & 27. Delivery timeframe- hit scope
Is this item or basket available for delivery in the customers' area, and if so what is the timeframe. This can help with drop off analysis, explaining why some users aren’t progressing.

27. Shipping method - session scope
When they purchased did they do a digital download, get express delivery, standard or pick it up in-store. All useful to know for analysis and retargeting.

Custom Metric 2 - cart value

Every time something is added to cart you add its value to this metric. This allows you to target high-value potential customers, they have some pricey things in their cart, maybe offer them a 5% discount to checkout. You would have to make sure not to include people who have purchased.

UX Dimensions

28. Breakpoint - hit scope
Given that most sites these days are responsive it would be good to know which breakpoint people are viewing the site on. Some people may be on a desktop but viewing on half the screen while they watch YouTube on the other half.

Other ideas?

I will add this as I go along, but feel free to suggest other ideas. You can also see what other people are tracking by using an analytics monitoring tool like dataSlayer.