>>528373480
follow whoever's pinging the route, try to get purple/orange weapon with the bosses weakness, all weapons have passives that basically make them talismans so beyond the weapon you're using, pick everything up that has a good passive for your character even if you won't actively use it.
bosses have weaknesses and resistances that aren't shown in game, but actually matter a lot.
read what your character's skills and ult are in the codex, and practice it 1 minute in the training grounds.
every time you conclude a run you get relics, these allow you to make builds for your characters.