any tips for character studies? i need to learn how they act before i start planning again
Writing what happens in episodes is a good place to start. By documenting their actions - moving from the canon video format to written words, you can extrapolate their views through thoughts, positioning (of paragraphs, scene breaks, grammar), and vocabulary. You'll find a difference between what you see and what you write, with advantages and disadvantages to both sides, but it's a great way to find your own thoughts on events/characters as a basis for analysis. It also helps with noticing particular trends (although beware of sore hands and looming insanity).
From there, you can then go into missing scenes. Many shows have to stick with a time limit and a certain focus, which can leave an opening for you to bridge the gap. Between episodes, within episodes, even scene changes! Knowing what happens before and after can act as a crutch for you to expand your horizon, allowing you a glimpse as to what may have happened and what change (or no change, which can be interesting in its own right) has occured + how those little moments impact the story.
Switching POVs is also a good thing to play with (especially in some series coughcough XY). Writing an episode from another character's point of view, whether it is another main, a side character, COTDs, or even going through another medium (e.g. chatrooms, news article, phone calls). Not only it helps with justifying the way the story is set (understanding the inner and outer world of the characters / giving you an alternate view of what characters are doing while not getting lost in just one POV) but also helps in understanding the world as a whole instead of leaning into Doylist explainations (which tend to be used a lot and breaks immersion). (In which Doylist analysis is great on its own! Looking into why particular actions happen due to the writers + the need to keep a series running is interesting and just as valuable as the Watsonian viewpoint. But it's such a cope-out when overused and doesn't lend any real character exploration because one has to attribute it to an outer force. The characters are props, yes. But there's a reason why a story exists, and handwave it away defeats the purpose of it. It is broken before it had a chance to start.) (In the end, both are good! But to me, balancing them is the game.)
One thing I would say is not a good way to go into things is with an expectation. If you go into canon expecting to see particular traits, or having a lens on that leans into bias (e.g. looking for relationships), it will poison the well. That's why it's good to take a step back and build up from evidence, rather than from the argument in mind. A character did this action: what reason could it be? What could influence them? What could change their reaction? How does their environment help/hinder this action? And so on. With enough evidence, a clearer picture will set in on its own, without any pushing. Applying critical lens can help, but I do find them a bit restricting, which is why I say it's best to just jump into canon and see what you can dredge up from there.