I would like to but even talking about the sites is outdated as well because it's not rocket science on how those sites work. There's plenty of beatmakers that sell just through social media, but I think for newbies they might still be overwhelmed by all the stuff involved. If you check some of the stuff I wrote years ago, some is outdated but the core still applies today.
Things like having your own website, social media presence, advertising, etc. I really do believe the best way to sell though is to simply connect to the right people because nowadays it seems like everyone is selling beats, is all over social media, taking out ads, etc. So instead of just going on Twitter and blasting everyone with "10 BEATS FOR 10 CENTS - ACT NOW!" posts, it's best to just socialize. But social media is everything but that.