How much do you actually earn in insurance, would love to hear about it from someone with experience.

Been invited to work for insurance company (friend of mine has worked for almost 10 years now),i recently quit my job and he was asking me if i wanted to work with him. He said his company will pay for all the tests and stuff. I know the more clients you bring, the more you earn but surely there will be months where you are unable to bring in clients how does that work? Asking him about his payment is a bit personal so would love to hear from someone who has worked or working in an insurance company. Thanks!