I've only been in the game a few months and unfortunately, I'm not in it anymore, but hopefully I can give you some pointers so you won't make the same mistakes that I did.

I agree that your mileage kind of varies as far as backtagging and cross-canon CR and it also depends on what kind of character you app. I was there with a sort of bratty and kind of anti-social character which didn't really help me, but since I was joining an existing cast I was able to build some interactions with people from other canons through my canon CR (if that makes sense). Being persistent really helps though and try to be early to the CR memes so you can tag other people and have them tag you back as well. Following through on them is also a big thing and will probably help you solidify a lot of your budding CR.

Getting a plurk also helps, but really, just trying to reach out and not being shy about it would probably put your character out there a lot. Be sure you have enough time and dedication to do all of that though because I definitely didn't even though I thought I did.

Whatever the case, good luck and I hope you have fun there!