Always disclose your affiliate relationship. Most visitors will probably understand that graphic ads will lead to your getting paid, but if you write a review or use an in-text link as a recommendation, you want your readers to know that may lead to compensation as well. This ensures you retain transparency and trust with your readers, but also, it's required by the FTC's endorsement rules.
But I'm not talking about any kind of link building. I'm talking about organic link building by getting out there and creating insatiable "anchor content" on your website, then linking to that content with equally-great content that's created on authority sites like Medium, Quora, LinkedIn and other publishing platforms. It's not easy by any measure. Google is far more wary of newcomers these days than it once used to be.
Affiliate marketing is commonly confused with referral marketing, as both forms of marketing use third parties to drive sales to the retailer. The two forms of marketing are differentiated, however, in how they drive sales, where affiliate marketing relies purely on financial motivations, while referral marketing relies more on trust and personal relationships.