You can improve Facebook Ads ROI by using the Conversions API to supplement Facebook's incomplete account of conversions via the pixel with data from your systems of record, such as orders created or forms submitted to your CRM. This allows you to train Facebook faster and at a lower cost, enabling more effective targeting and increased conversion rates. To do this, you'll need to configure your Facebook Ads pixel tracking, model your data for the Conversions API, import conversions into Facebook Ads using a reverse ETL tool like Census, and ensure that your data meets the requirements for reporting, ads attribution, and deduplication. By leveraging the Conversions API, you can increase the volume of conversion signals sent to Facebook Ads, resulting in improved ROI and more effective targeting.