One of the most sought after and highly recommended course is this one on Guide to Effective Affiliate Marketing Strategies by Kudus Adu. Not only does he focus on create an affiliate marketing strategy, he focuses on best practices to create money pages, tells you how to build your email marketing list and how to profit from it. He clearly asks people looking for ‘get rich quick strategies’ to stay away from the course.
As for your question about which affiliate program to join, I cannot give you an answer for that because that’s totally depends on the niche you’re in. I’m not familiar with your niche so I can’t give you any recommendation for that. That’s for individual private affiliate programs. You can also check out the common affiliate networks like Amazon, ClickBank, Shareasale, CJ, all these.