Any unnatural linking will always be noticed at some point + penalized.

Better to have a site which is so valuable people naturally link to the site.

Then market that site.

I would recommend implementing Tier 2-3 links, but don't do it in a spammy way or abuse your anchor text ratios. If you choose legitimate web2.0s and aren't divvying away from your industry too much, they are pretty penalty proof. Only when you encounter using low quality PBNs and low quality web 2.0s do you run the risk of penalties.

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!)