Any spot where there is a high volume of daily accesses will grant you referrals. Active Facebook crypto related groups used to be a good environment to promote referral links, but I suspect the algorithm was internally changed, because I can't find bitcoin groups anymore on the search bar. It says no results were found, even though I'm member of many groups on that category. I'm almost sure bitcoin content was silently censored there, as I'm stucked with the same amount of referrals for some months already, while before I had a flux of at least 2 new referrals every few weeks*.

Probably the most efficient methods right now are youtube, twitch and similar streaming live content platforms. You need a sensationalist title and thumbnail for your video, then you can share it with most people as possible and hope they will click it. Personally I don't make use of this method and don't like it, because I hate clickbaits. I'm just telling how things work.

* I share part of my comission with my referrals, so it's an extra incentive for them to sign up through my link and that is the reason why I had that flux of new referrals. You can also try doing the same...