Create a campaign with a single objective you can live with — clicks, reach, or conversions if that bidding type is live on your account — a budget you can hold for at least a week, and one offer. Add an ad group with a default destination URL. Resist catalog-everything on day one. Thin reporting plus many SKUs is how you learn nothing and still spend the test budget.
The structure is familiar on purpose: campaign, ad group, ad. Campaign holds budget, dates, geo, and objective. Ad group holds bid and context hints. Ad holds the chat card: title, body, image, URL. If product-feed campaigns exist on your account and you are ecommerce, consider a feed campaign for SKU matching and a separate standard campaign for a flagship offer. Do not mix a brand story and a 40-SKU dump in one ad group. You will not see which conversation matched which item, and the card will look like a catalog accident.
Name objects like a grown-up: market, offer, hint theme, date. Future you will not remember what 'test 3' meant. Set end dates on tests so a forgotten beta campaign cannot keep spending after the team moved on. If custom audiences are available, use them as include or exclude lists you understand (buyers, high-value customers, unsubscribers), not as a substitute for context hints. First-party lists refine; they do not describe the conversation. The conversation is still the targeting primitive on this platform.