The most common Google Ads bidding mistake isn’t choosing the wrong strategy. It’s choosing a strategy that requires data you don’t have yet.
I’ve taken over accounts running Target CPA with 11 conversions in the last 30 days. The strategy needs ~50 to work. The account was in permanent learning mode, costs were volatile, and the business owner thought the ads were broken.
The ads weren’t broken. The bidding strategy was wrong for where the account was.
What Are the Main Google Ads Bidding Strategies?
Manual CPC
You set the maximum bid for each keyword manually. Full control, full responsibility for optimizing. No algorithm learning.
Use when: New campaigns with no conversion history. Accounts with low conversion volume (under 30/month). Situations where you need precise control over individual keyword bids.
Maximize Clicks
Google automatically sets bids to get the most clicks within your budget. No conversion optimization — purely traffic-focused.
Use when: Building initial traffic data for a new campaign. Keyword research phase where you want to see what queries you appear for. Campaigns where awareness matters more than conversions.
Enhanced CPC (eCPC)
Manual CPC with Google automatically adjusting bids up or down based on the likelihood of conversion. A middle ground between manual and fully automated.
Use when: You have some conversion data (15-30/month) but not enough for full automation. You want algorithmic help without giving up full control.
Target CPA
Google automatically sets bids to get conversions at your specified cost per acquisition target.
Use when: Your account has at least 30-50 conversions in the last 30 days. Conversion tracking is accurate. You have a clear CAC target based on your business economics.
Target ROAS
Google sets bids to achieve your specified return on ad spend.
Use when: eCommerce with transaction revenue data. You have 50+ conversions per month. Revenue values are tracked accurately in Google Ads.
Maximize Conversions
Google spends your budget to get the maximum number of conversions, regardless of cost.
Use when: You want to grow conversion volume quickly and cost is secondary. New campaigns you want to move from manual to automated — Maximize Conversions is a gentler entry point than Target CPA.
How Much Conversion Data Do You Need for Smart Bidding?
Google’s official guidance is 30+ conversions in the last 30 days. My experience: 50+ produces noticeably more stable performance.
Below 30 conversions per month, automated bidding strategies spend significant time in ‘learning’ mode, where bids are less predictable and costs more volatile.
For new accounts, I almost always start with Manual CPC or Maximize Clicks, build conversion volume for 60-90 days, then transition to Target CPA once the data is there.
What’s the Most Common Bidding Mistake?
Switching bidding strategies too often.
Every time you change your bidding strategy, the algorithm resets its learning. If you switch from Target CPA to Manual CPC back to Target CPA within a few weeks, the algorithm never accumulates enough data to optimize effectively.
Set a strategy. Give it 4-6 weeks minimum. Evaluate on 90-day trends, not week-to-week swings. Change strategies intentionally, not reactively.