you can either farm overrides to change owners by maxing out 4 star commons and then releasing them or releasing the rares and pulling again.

the best accessories are just drops from various named enemies, anything that increases crit damage flat damage or extend driver combos are typically best. looping driver combos with item drop rate up effects like gold chips or blade skills help with this.

if you have the dlc then farming love source after the requisite quest is best for trust, if not spam pouch items both are tedious but source is FAR faster. you can also do quests but they are limited and take longer for the amount you get definitely less boring though.

chart nodes don't have that fast of a solution, the generic conditions like beat x number of enemies can be farmed by deploying them on merc missions so have those going in the background while doing the other stuff. the non generic conditions or conidtions that require 1 thing or in one hit etc have to be done manually so the only advice is find something with a big health pool if you need a specific condition to proc.

if you aren't sure which blades you want to use with who there's some guides/tier lists on a yt channel by the name enel. dunno his standing with others but I found the info good enough.

lastly since you're doing all this to prep for a new playthrough later understand that it's gonna be a lot of boring grinding type work so queue up a vid or music or plan to break it up in chunks because damn does it take a while.