The document provides tactics for marketplace operators to improve quality by establishing a virtuous cycle. It discusses the importance of optimizing screening, training, optimizing matches, retaining high quality participants, and expelling low quality ones. Specific tactics discussed include using data and limited upfront requirements for screening, tailoring training to expected lifetime value, using feedback combined with behavioral data to optimize matches, rewarding top performers to boost retention, and leveraging referrals to attract more high quality participants. Case studies from marketplaces like Faber, Rev, and Outlier/Masterclass are presented. The overarching goal is to design marketplaces where quality begets more quality through strategic application of these tactics.