Google Ad Manager (GAM) is an extremely powerful tool — but come on, it’s not particularly newbie-friendly. Whether you’ve just started with GAM or have been working with it for some time, it’s simple enough to fall into small errors that can disrupt your ad performance (or heck, your revenue).
So let’s spare you the headache! These are the top 10 most common Google Ad Manager mistakes people make — and how to avoid them.
1. Setting the Incorrect Time Zone or Currency During Setup
This one’s a quiet killer — you can’t switch your time zone and currency once you’ve set it.
❗Why it matters:
Reports, campaign timing, and billing can all get confusing if these settings don’t match your actual location or ad agreements.
✅ Fix: Double-check both before submitting during the account setup. Think long-term!
2. Not Structuring Your Inventory Properly
Creating ad units on the fly without a naming convention or hierarchy? It’ll come back to bite you.
❗Why it matters:
A messy inventory makes it hard to manage and report on ad performance.
✅ Solution: Outline a good hierarchy for your ad units — use something such as site sections, device types, or locations (e.g., homepage_header_desktop).
3. ⚙️ Missing Targeting of the Proper Ad Units in Line Items
You set up your ad unit… but ads are not being displayed? Maybe you did not target it effectively within your line item.
❗Why it matters:
If the line item isn’t linked to the correct ad unit, the ad won’t serve — even if everything else is perfect.
✅ Fix: Always double-check targeting when setting up line items, especially if you’re working with a lot of ad units.
4. Neglecting to Set Line Item Priorities Correctly
GAM uses a priority system to determine which ad to serve. If you don’t configure these in the right way, high-paying ads will be blocked by low-priority ones.
❗Why it matters:
Misconfigured priorities = lost revenue.
✅ Fix: Learn the difference between sponsorship, standard, network, bulk, and house priority types — and use them wisely.
5. Not Using Key-Value Targeting
Key-values are your best buddies when it comes to granular targeting — but many users never lay hands on them!
❗Why it matters:
Without key-values, you’re missing out on sophisticated targeting such as page categories, user types, or custom placements.
✅ Fix: Leverage key-values to deliver more personalized ad experiences and better performance.
6. Not Testing Your Tags Correctly
Copy-pasting ad tags and hoping for the best? Dangerous game.
❗Why it matters:
Even a single incorrect character in the ad tag can prevent your ad from appearing.
✅ Solution: Utilize the Preview and Delivery Diagnostics tools in GAM to test it all before going live.
7. Overloading Pages with Too Many Ad Units
The more ad units, the more money, right? Not necessarily. Overloading your page can actually harm user experience — and even break Google policies.
❗Why it matters:
Too many ads = slow load times, increased bounce rates, and possible penalties.
✅ Solution: Keep it simple. Quality over quantity always pays off in the long term.
8. Not Regularly Monitoring Reports
Setting and forgetting your campaigns is a no-no.
❗Why it matters:
If something goes wrong, you may not realize until you’ve lost days (or weeks) of revenue.
✅ Fix: Allocate time on a weekly basis to review performance reports. For trends, mistakes, or ways to improve.
9. Not Linking to AdSense or Ad Exchange
If you aren’t operating direct deals as yet, you can still monetize your remnant inventory — but most users ignore this.
❗Why it matters:
Empty ad space = zero dollars.
✅ Fix: Associate GAM with your AdSense or Ad Exchange account in Admin > Linked Accounts to ensure all inventory is being monetized.
10. Not Staying Current with Updates & Best Practices
Google is constantly experimenting with the platform, and the ad industry standards are changing daily. If you’re not staying current, you’re behind.
❗Why it matters:
What was successful last year may not be successful today.
✅ Solution: Subscribe to Google’s news or read reliable ad ops blogs (or gosh, just just keep coming back here ).
Last Words
Google Ad Manager is a beast — but with some taming, it will work magic on your revenue and ad delivery control.
Avoiding these common mistakes will save you time, frustration, and potentially a lot of money. Whether you’re just getting started or scaling your ad strategy, a little extra attention goes a long way.
Got questions or tips of your own? Drop them in the comments below — let’s help each other grow!