I've searched for an answer for a few hours now and every site I've come across is just a copy of the last one, covering only downloading in most cases.
What are the best practices for uploading and seeding (legal) original content to stay as anonymous as possible?
Best practice for seeding is to verify and ensure that you are fully connectable (port forwarded). Check that your torrent client's incoming connection port is actually connectable from the internet, you can use any port test website for that e.g. https://www.canyouseeme.org , https://www.yougetsignal.com/tools/open-ports , etc.
If you are using a paid torrent friendly VPN service then verify that the VPN service itself allows port forwarding and follow their instructions to set that up. (the port forward you set up in the VPN service is the port you would configure in your torrent client's incoming connection port setting).
For the port forward itself you may want to configure a port number in the ephemeral port range (49152–65535) particularly if your ISP has a habit of throttling bandwidth on lower port numbers. That may not matter as much if you're using a VPN.
I don't know what to recommend with the other stuff, private trackers already have their own rules on what they allow to be uploaded to their tracker. Best to read through the private tracker's rules for that.
Unfortunately lemmy.world admins blocked it, along with most piracy communities, so you probably can't see it on your end while logged in. You'd need to create a different Lemmy account elsewhere to participate.
It's kind of amusing, almost all the recent posts at this community ( !piracy@lemm.ee ) are from lemmy.world users that can't see any of the bigger piracy communities.