What are the main bidding strategies in Google Ads, and how do you choose between them?

Manual:

• Manual CPC — you set bids yourself. Maximum control, but does not use Google's per-auction signals. Useful for very low-volume accounts where automation cannot learn.

Automated, by objective:

• Maximise Clicks — traffic volume. Reasonable for a brand-new campaign gathering data, but it optimises for clicks, not customers.
• Maximise Conversions — as many conversions as the budget allows, with no cost constraint. Use when volume matters more than efficiency.
• Target CPA — conversions at a specified average cost. The standard choice for lead generation.
• Maximise Conversion Value / Target ROAS — optimises for revenue rather than conversion count. The right choice for e-commerce, where a 500 order and a 50,000 order are not equivalent.
• Target Impression Share — for visibility goals, typically brand defence.

How to choose: smart bidding needs conversion data — roughly 30 conversions in 30 days for Target CPA, and more for Target ROAS. Below that, it cannot learn and you are better off with manual or Maximise Clicks while you build volume.

Note: Two practical points: accurate conversion tracking is a prerequisite, since smart bidding optimises towards whatever you tell it is a conversion; and expect a learning period of one to two weeks after any change, during which you must not keep adjusting.