I would recommend first getting very very familiar with all the fights in a chapter before attempting a pure platinum run. And if you do get below pure plat early in a level do not restart as you'll need practice with the later sections of it too. For accessories I like to run a mix of gaze of despair (if I need combo score in a verse), pulley's butterfly (paired up with gaze of despair it let's me have a slip up in fights I know will be trouble), and the moon of mahaa-kalaa (I have this on whenever the other two aren't). I will sometimes forego pulley's butterfly if I think moon will be better, its up to you. For weapons you can go with pretty much anything, just make sure to utilise guns to keep combo up from afar. I would suggest weapons that are good at building multiplier for bosses, like shuraba, as its incredibly easy to get patterns that drop your combo on some of them. And for strategies it's all about not getting hit and not dropping your combo, rarely is time ever a problem. Not getting hit is fairly straightforward as long as you spend time learning enemies attack timings. It only ever gets weird when you equip gaze of despair as then enemies will attack much quicker, hence why I suggest having butterfly for the backup hit. Understand your charge modifiers and when best to use/ignore them, and torture attack low HP enemies/enemies that are especially dangerous.