Simply focus on content and you will never have an issue with having to worry about penalties from Google again.

The secret is...well there is no secret. Stop focusing on link building and all this artificial crap. Google KNOWS it is artificial, which is why you are on here asking this question instead of making money.

Product 3 high quality pieces of content weekly for your money sites answering REAL questions consumers have that are searching Google. Questions related to your niche. That is the key.

The best affiliates in the world get backlinks built for them without trying. In other words, they don't focus on it.

Just focus on content production and do your on-page SEO with Yoast. Do 3 pieces of content a week for 6 months and you will see what I'm talking about in your Google Analytics (and in your bank account!)