What is a bid strategy?
A bid strategy tells the ad platform what to optimise your bids toward — clicks, conversions, or conversion value.
The choice depends almost entirely on how much conversion history exists. Automated conversion strategies need data to learn from, and applying one to a brand-new campaign typically produces either no delivery or wildly expensive results while it flails.
Google's own guidance is roughly 15 conversions in the trailing 30 days before Maximize Conversions is appropriate. Below that, maximising clicks with a cost-per-click ceiling is the honest starting point — it gathers the data the smarter strategies need.
Value-based strategies like target ROAS need more history again, because they model a distribution of order values rather than a simple rate.