If you're already making sales in a broad campaign and later on the vendor is happy to supply you a lookalike list, should you then test the ad with a lookalike list against broad?

Yes, test the ad with the lookalike list against the broad audience to compare performance.

For more detailed instructions, please refer to Module 2 - 5 Rev Share vs CPA - Getting Your Affiliate Links & Connecting with Vendors.

Also, don't forget to register for our weekly live Group Mentorship sessions. They are key for getting extra help and deepening your understanding of the program. You will automatically receive weekly invite emails on Tuesday of each week with email subject lines that always begin with "[AdV] - REGISTER" where you can register for each week's calls.