Since you've asked this question, I will assume that you're already aware of what affiliate marketing is.
With this in mind, I will share my experience of helping people with affiliate marketing along with my own affiliate marketing blog.

So here's what I did for my blog:

1. I picked up a niche that is profitable in terms of selling. For me it was electronics, gadgets. I was good at understanding how it works, so it makes easier for me to sell it via my blogs.
2. I created content around all the gadgets that we use in day to day to lives. The content majorly focuses on problems people are facing while using the technology products. This involved researching on the keywords, keywords that people use to describe the problems.
3. Research was the most lengthy process and is the most fun part. It tells you exactly where the pain point is. Furthermore, it is partially a one time thing. Once you do a decent amount of keyword research, you already have a lot of content to create on. Which will further trigger more problems as you interact more.
4. Taking care of SEO of my blog, as I wanted to reach to everyone who probably faces the same issue and searches for a solution online. I have researched enough to create awesome content that solves the end user's problems. So this, along with a decent SEO, I was able to rank at top of the SERPs pretty fast.
5. Keep researching for all the problems that users face, this time wider and on a large scale. I dug up reddit, Quora, Google search, YouTube etc for specific gadgets, & technology products/service.
6. Meanwhile I served people the solution they're looking for, I also kept building an email list which I would use as a sale blaster. Whenever there's a sale coming up, I'd send out an email with exactly instructions to enjoy the sale and my affiliate links in the email. This ensures, we two don't miss out on this opportunity.
7. I also kept growing social media accounts, serving the community with free but brief content and divert traffic to my blog, where the real business happen.

This was how, I would cover all three streams of online marketing in my favor. This is how I have done for my blog(s), my client's business and this is how I would suggest you to do the same.

I hope this helps. I'd love to help you with your business in terms of SEO, Social media marketing & email marketing.
Let's keep in touch.