7 Google Ads mistakes that burn your budget and how to fix them

You've launched Google Ads campaigns. The budget is running, the clicks are coming in, but the results aren't following. You're not alone: most of the Google Ads accounts we audit show at least 3 of these 7 structural mistakes. And they can eat up hundreds of euros a month without you noticing.

The good news? Each one can be identified and fixed. This guide reviews the 7 most common and most expensive mistakes, with the fixes to apply right away.

📌 RECOMMENDED READING FIRST

If you're new to this, start by understanding what Google Ads is, the auction system and the 6 campaign types before reading this article.

76%

of Google Ads budgets wasted on irrelevant searches (WordStream, 2023)

3.5x

average ROI observed after fixing structural mistakes in audited accounts

1. Google Ads mistake #1: keywords that are too broad with no negatives

This is mistake number one, and by far the most expensive. By default, Google Ads uses broad match. In practice, if you target "sports shoes", your ad can appear for "kids' sports shoes", "cheap shoes" or "how to clean shoes": searches unrelated to your offer.

🔴 A REAL EXAMPLE

A client selling HR software was targeting "human resources management" in broad match. Its ads appeared for "HR management courses", "HR books", "free HR training": budget wasted on people looking for training, not software.

The fix

• Switch your main keywords to exact match or phrase match

• Build a negative keyword list from launch (competitors, generic terms, training…)

• Check the "Search terms" report every week to spot irrelevant queries

2. No conversion tracking: Google Ads optimises in a vacuum

Without conversion tracking, Google Ads doesn't know what works. It optimises in a vacuum, and so do you. Yet around a third of the accounts we audit have no properly configured conversion.

⚠️ WHAT THIS MEANS IN PRACTICE

Without tracked conversions, you can't use smart bidding strategies (target CPA, target ROAS). Google shows your ads based on its default signals, which don't necessarily match your ideal customers.

The fix

• Set up at least one primary conversion: purchase, form submission, phone call

• Use Google Tag Manager to deploy the tag without touching the code

• Check that the status is "Active" in the Google Ads interface

3. Search and Display in the same campaign: an expensive mix

By default, Google suggests enabling the "Display Network" when you create a Search campaign. It is a box ticked by default, and it is a trap. Search and Display audiences are radically different: one is actively searching, the other is being interrupted. Mixing them dilutes your performance and skews your data.

⚠️ INTERFACE TRAP

Google presents this option as an advantage. In reality, it shifts part of your Search budget, often the most profitable part, to much less qualified Display placements. Always untick this option.

The fix

• Create separate Search and Display campaigns, with distinct budgets and goals

• On existing campaigns: Settings → Networks → untick "Display Network"

4. Sending traffic to the home page

Your ad promises a specific solution. If the user clicks and lands on your generic home page, they have to look for what was promised themselves. The vast majority leave in under 10 seconds.

Every ad should lead to a dedicated landing page that continues the ad's promise exactly: same headline, same benefit, same CTA.

✅ THE MESSAGE MATCH RULE

If your ad says "HR software for SMEs, free 30-day trial", your landing page must show that benefit immediately above the fold. Not a generic slider. The same message, visible straight away.

5. Using the wrong bidding strategy

Google Ads offers many strategies. The common reflex is to choose "Maximise clicks" because it seems logical. Wrong. This strategy chases the maximum number of clicks for your budget, with no regard for their quality or relevance.

6. Neglecting Quality Score

Quality Score is the 1 to 10 rating Google gives each keyword based on ad relevance, landing page experience and expected click-through rate. A low Quality Score means you pay more than your competitors for the same position, sometimes two to three times more.

💡 HOW QS AFFECTS YOUR ACTUAL CPC

An advertiser with a QS of 8 can get the same position as a competitor with a QS of 4 while bidding half as much. That is the Ad Rank principle: position = bid × Quality Score.

The 3 levers to improve your Quality Score

• Ad relevance: the targeted keyword should appear in the headline

• Landing page experience: a fast, mobile-friendly page with content related to the keyword

• Expected CTR: well-written ads with complete assets

7.Changing your campaigns too often, or not enough

On one side, the advertiser who edits the campaign every day out of impatience prevents the algorithm from stabilising, as each change triggers a new 7 to 14-day learning phase. On the other, the one who launches and forgets: irrelevant keywords pile up and performance quietly deteriorates.

✅ THE RIGHT OPTIMISATION RHYTHM

• Daily: budget spent, anomaly alerts

• Weekly: search terms report, adding negatives, key metrics

• Monthly: bid review, testing new ads, conversion analysis

Summary: checklist of the 7 mistakes to fix

• Keywords in exact or phrase match (no broad match without negatives)

• Conversion tracking active and verified

• Separate Search and Display campaigns

• Every ad points to a dedicated landing page

• Bidding strategy suited to your data level and goal

• Quality Score monitored and optimised

• A regular optimisation rhythm, neither too frequent nor too rare

Recognise one or more of these mistakes in your account?

A free Google Ads audit identifies within 48 hours exactly where your budget is being lost, and the priority fixes to apply.