FTC disclosure guidance for affiliates

US law (FTC Endorsement Guides, 16 CFR Part 255) requires you to tell your audience when you earn money from a recommendation.

Put the disclosure next to the link or claim, before the "more" fold, in plain words: "I earn a commission if you buy through my link."
Video: say it out loud and show it on screen. Short posts: #ad or #affiliate at the start, not buried in hashtags.
Only share honest opinions from real use. No income or results claims we have not published.
A platform's built-in "paid partnership" label is good; add your own words as well.

Reference: ftc.gov "Disclosures 101 for Social Media Influencers". This is guidance, not legal advice.