Google Ads Optimization Guide: From Quality Score to Smart Bidding

Key takeaways

• Google Ads optimization works in a fixed order: fix relevance and Quality Score first, then let Smart Bidding scale what already converts.
• Quality Score directly discounts your CPC. WordStream’s analysis of client accounts found a Quality Score of 10 cut CPC by about 50% versus an average score of 5.
• Target ROAS needs at least 15 conversions in the past 30 days on Search and Shopping campaigns, according to Google Ads Help.
• Enhanced CPC was deprecated for Search and Display campaigns in March 2025, so the real choice now is manual CPC or a Smart Bidding strategy.
• Every change to a target, budget or conversion goal can restart the learning phase, so batch changes instead of making them daily.

What is Google Ads optimization?

Google Ads optimization is the practice of improving relevance, bidding and conversion tracking so your ads win better positions at a lower cost per conversion. It spans Search, Shopping, Performance Max, Display and YouTube campaigns.

Two systems decide most of your results: Quality Score, which sets what you pay per click, and Smart Bidding, which decides how much to bid in each auction.

How does Quality Score affect what you pay?

Quality Score lowers your CPC because Google divides the Ad Rank of the advertiser below you by your Quality Score to set your price. A higher score means you pay less for the same position.

Google rates three components, each as above average, average or below average:

• Expected CTR: how likely your ad is to be clicked for that keyword.
• Ad relevance: how closely the ad matches the intent behind the search.
• Landing page experience: how useful, fast and relevant the page is after the click.

Source: WordStream’s Quality Score analysis. Google calculates the real score as a non-integer, so treat these as directional, not exact.

Which Smart Bidding strategy should you choose?

Choose your Smart Bidding strategy by how much conversion data you have and whether your conversions have different values. Smart Bidding uses auction-time signals such as device, location, time of day, audience and query to set each bid.

Source: Google Ads Help, About Target ROAS bidding. The 30-conversion Target CPA guideline is widely cited by practitioners, including Store Growers.

A practical path is to start with Maximize Conversions, then add a target once CPA has been stable for a few weeks.