I've recommended Spiritual Satanism to people on 4chan before, in particular by telling them how they can use meditation and spirituality to enhance their sex life and overcome mental health problems such as anxiety. That tends to get those people interested right away. There's always the contrarians that say awful things like "Satanism is jewish", but that gives me an opportunity to explain that it's actually quite the opposite, and there are always people who take what I say seriously and express that they resonate with it.
I wouldn't actually recommend doing activism on that site, since it's is such a degenerate cesspool at times that it ends up harming my own mental health, and I have to take breaks for several months at a time and only go there when I'm really bored and want to vent about stuff that no one would ever take seriously anyway. But some of the people who use that website are actually interested in self-improvement and spirituality and just don't know how to get started, and it's possible to have lengthy, uncensored conversations which can very be useful when it comes to giving people advice. It's usually the soft-spoken ones that seem the most interested.
It's always satisfying to see when people express curiosity about the stories I tell, then remain interested even after I reveal that all the positive things I mentioned are actually thanks to Satanic meditation from the Joy of Satan. About five people even expressed a strong interest in dedicating, and I know at least two actually went through with it and started doing the F-RTR. I know it's only a handful, but I like to think that every little bit counts.