On the topic of Reqs:
The Chien-Pao suspect was my first attempt at Reqs, and I was able to push myself up from a 68 GXE ceiling on my first attempt to a 76 GXE ceiling on my third attempt. I didn't get them in the end, but I saw enough improvement in my ratings that I think it's worth sharing what helped me.
1. Make sure your team is rock-solid. To get from 1000 to the 1700ish you'll need for Reqs, you're going to see every different type of team. You really can't afford to lose on team preview to anything common if you want a realistic chance. If you're already getting caught out low ladder by certain archetypes or individual pokemon, make appropriate changes to your team or strategy. There's no shame in using Meta pokemon or those top of the usage list. This is a tough Meta and you really can't afford to be carrying any passengers. If you're struggling to build a team, there's nothing wrong with using someone else's team.
2. Appreciate that you likely won't win every game and try not to get tilted. Sometimes you get frozen by Ice Beam and stay frozen 5 turns in a row. It happens. Sometimes you miss a Draco Meteor and it costs you the game. It is what it is. Being able to differentiate between losing due to hax (which happens!) and losing because of a team-building issue or because of a misplay is a crucial skill. Don't throw your entire team away because of a loss. However, if you lose 3/4 in a row the same way, that might be a team-building issue that you can fix.
3. Going back and watching your own replays of wins and losses is going to help you to see things you've done well or poorly and will allow you to improve your game. The more of your own replays you watch, you'll start to pick up on the things that you do subconsciously. This will help if you've got any bad habits that you might not be consciously aware of.
4. Play slowly, and take care of your GXE. It's going to go up more quickly the more games you win in a row. If you lose, don't rush straight back into a new game. Watch the replay, see where things went wrong, and try to determine if you lost due to misplays, team-building, or something else. If you notice that you keep losing because of the same thing, this will help you identify the issue, and there's a wealth of knowledge on this forum, youtube, etc. relating to how to fix that issue.
5. Try to make achievable progress. By that I mean, if you're a consistent 50 GXE player, the harsh truth is you're probably not going to get Reqs. BUT, that doesn't mean you can't try, and it doesn't mean you can't improve. If you're at 50, try to set yourself a target of 60 GXE, and use the tips in this thread to achieve that. If you're at 60, aim for 65, and so on and so forth. 80 GXE is objectively hard to reach and there's a reason the majority of the playerbase won't hit it.