The key components for joing an affiliate program are:
1) Reliability of the company running the program and the marketing support they provide (Reputation and Location)
2) The type of product or service they want the affiliate to advertise (i.e sub-prime loans, weight loss drugs vs branded products)
3) Transparency of their platform where you track your leads and payments
4) Charge backs and speed of payments
5) Any hidden fees

Example: https://www.udemy.com/course/leadsmarket-affiliate-certification-program/?srsltid=AfmBOorV8SZsOYkQsyAUTAo-u-zrcMXIBa6NOjw5udZm39DuKCEtbOco