Feel free to add in the comments!!
No particular order of importance
-Respect the dibs
-Always break off from the jumpmaster before landing
-If someone pings a location during the drop, let them land there and find somewhere else to loot
-Always do your best to revive teammates and recover banners/respawn teammates. This is a team game!!
-Ping enemies before engaging to let your teammates know of their location (unless you’re sniping and see a Wraith, if that is the case, speak on the mic and tell them the cardinal direction/compass degree)
-Unless it’s a spectacular opportunity, let your teammates catch up to you before engaging enemies
-Don’t be stingy with meds. You’re all on the same team, if you have full health and a med kit/syringes, and your teammate has low health and no heals, drop the med kit/syringes for them. Don’t worry you’ll find more. Same goes for shield cells/batteries.
-This one isn’t always expected, but is polite nonetheless; let the person who killed an enemy loot their deathbox before you do
-If a teammate is eliminated, don’t loot their deathbox after recovering their banner, even if they have something you really want (an exceptions to this is if your teammate dies before the fight is over and you need ammo/grenades to defeat an enemy squad)
This is obviously an incomplete list, add on to it!!
Source: https://www.reddit.com/r/apexlegends/comments/cb8gzi/thread_of_apex_legends_etiquette_and_common/