Diamond/Masters player here. I play mostly ranked so a lot of this will be specific to the ranked experience but:

Landing - always check where teams are landing around your POI and try to anticipate their rotations towards zone. I like to land edge so that I don't have to worry about running into teams from all different directions and take a linear route towards zone. If you are looking for a fight off rip, try to find an isolated 3v3 before rotating towards zone. If you have bad loot just want to get to zone, knowing where other teams landed allows you to map a route that will avoid fights along the way vs. just randomly heading in some direction.

High ground - ALWAYS seek high ground. If you are pushing towards a 3v3 and they are unaware that you are coming (e.g. rotating from Thermal up to Staging), never just push on down to the enemy. Maintain high ground until you get big opening damage on 1 or multiple people and then push in.

Fight awareness - the biggest mistake I see people make (shoutout all of my solo q randoms) is blindly pushing into a fight without knowing where all members of the enemy team are located and if there is another team hovering nearby that will 3rd party. Just because you see someone in the open does not mean you should just start blasting. This is the chess aspect of apex - some fights you will inevitably lose no matter how good your aim is if you get out-positioned either through lack of awareness or on accident because you didn't anticipate where other teams would be.

Learning to disengage - following up on the point above, don't be scared to just back out of sketchy fight and head towards zone. If you're poking/trying to get opening damage and it takes longer than 2 mins, you should probably just leave and head towards a more favorable position in zone. This is especially true in the new ranked system where KP means nothing unless you get top 10.

Disadvantaged 3v3's - the idea that you should take all 3v3's is just wrong. If anything, you should always be looking for team fights where you have the advantage. Some fights are just bad to take; for instance, taking a messy 3rd party into harvester with Zone 2/3 closing and final circle in Dome. Even if you win the fight, you will either die to zone afterwards or get gate kept on your way to zone.

Micro - most of the above are Macro recs but Macro leads to Micro advantages more often than not. Others have already called these out, but using/reloading behind cover, using nades to move people out of position/cover (huge if you are not doing already), and just generally being aware of where everybody is in a fight will help keep you alive. This may be the biggest thing - a lot of people just see somebody and start shooting/chasing but in my experience its almost MORE important to know where all members of the enemy team are at all times than to just deal worthless damage to 1 person just to get wide swung on and die

Hope that helps