If you’re a blogger, start by going through your analytics and finding your most popular posts. In Google Analytics (GA) you can find these pages by going to your GA Dashboard > Behavior > Site Content > All Pages. Examine the ones at the top of the list that bring in the most traffic. Are there any affiliate products or services you can naturally include in them?
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.