A conversion ad is a form of digital ad that can be used to generate leads. It may be specific to an industry or offer a product or service.
A conversion ad is different from standard ads because it focuses on particular actions instead of just displaying the product on the page. A conversion ad is also more likely to be seen and clicked because it has clear call-to-action.
The best target action (standard or custom event) for bidding is one that is as low in your conversion funnel as possible and has at least 15-25 conversions per ad set each week so that Facebook's optimization algorithms can guide your advertisements' delivery. This is just a general rule of thumb: the more the merrier.
In order to create a conversion ad, you need to identify what your target audience is and design the ad accordingly.
Keep in mind, however, that after each new edit, you must give Facebook at least 24 hours to alter the performance of your advertising. Consider waiting at least 24-48 hours after making significant modifications to your campaigns before drawing any conclusions.