For TV, the best is BTN. They are currently closed outside of personal invites, so virtually impossible to join at the moment. Some more accessible alternatives would be MTV, BLU, and FL.

For music, the best is RED. They have a hard economy, so if you want any easier economy and overall experience the best alternative is OPS. Soulseek is also a must if you are looking for music.

For games, the best is GGn. Nothing really comes close in the private tracker ecosystem. There is PxC, but they are light-years behind in terms of breadth and depth of content. More accessible alternatives would be in the public tracker space like 1337x and Rutracker.

For audiobooks, the best is MAM, which is also the easiest private tracker to join for someone who is not on any private trackers yet. Start here, even if you're not looking for audiobooks. Seriously, this is the best private tracker to learn the ropes on.

For ebooks, the best is BIb. I may be wrong, but I don't think they are recruiting at the moment. A far more accessible alternative would be MAM.

For literally every single person who has asked, is currently asking, or will ask in the future some iteration of "how do I join these trackers/where do I start/can you invite me to tracker x," the answer stays the same: join MAM or RED via irc interview, increase your user class with time and a little effort, and then you will unlock a subsection of forums where other trackers offer recruitment threads. Read the recruitment requirements, make sure you meet them, message the recruiter asking for an invite, wait patiently, and you'll receive an invite link to join said tracker. Congratulations, you are now a member of your second private tracker! Repeat this process on tracker #2 until you have accounts everywhere your little heart desires. You are now "climbing the ladder."

What's at the top of the ladder? The cream of the crop trackers, those best in class communities that everyone wants but very few put in the work to actually join: the "cabal" sites. They are called cabal because the staff from cabal trackers will reach out to each other if you get caught breaking the rules, and you're likely to be banned across the board on all cabal trackers you are a member of if your rule violation is bad enough. There is very little slack given at this level, so you best know what you're doing.

And once you've climbed to the top, diversify. There are best in class usent indexers like the ones that prefer to not be discussed publicly, there are ddl sites like SIG, wdma sites that live on like unicorns as the piracy landscape shifts with gains and losses, forums specifically for piracy and tracker discussion, and of course...magic sites (good luck, better pack a lunch).

It's a fun ride, being a part of all this. But it isn't for everyone. Just find whatever works best for you and enjoy it for as long as you can.