Very tough question.
The best answer I can give is that it's a constant battle between "what would I do?" and "what would ____ Nihil do?". I almost always defer to how they would behave in a given situation, unless I don't have a good feeling for how they would react, or unless there's a very good reason. Thankfully, a lot of their character traits tend to be compatible with mine, so we would think alike (for instance, Sakura's strategic outlook on the wars of the cluster) in a fair number of instances.
I understand that this is "RP on easy mode" to some degree, in that it doesn't push me too hard to understand how they think. However, I live for combat in this game, that's what I joined for, RPing only came as an add-on when Sak joined Star Fraction a long time ago, and I found it was a nice addition to help distinguish my characters from one another.
I try my best to stay away from staged or planned events, preferring not to delve super-deep into the plot and setting, but rather focusing on person-to-person interaction for my enjoyment. I try and be spontaneous and reactionary as possible, figuring out opinions on current events and conversations as I go without a pre-planned, high-level script for how I want the character to develop.
In short, whatever happens, happens. Sakura went from essentially a mining corporation's security guard in a Ferox to pirate due to being backstabbed by "friends", and over time she's gone down that path further and further. Her sisters are still somewhat blank slates, but only really due to lack of RL time on my end, or circumstances shaping their growth as individuals. I don't know what's in store for any of them - case in point, the one up in Caldari space, Akusa, was put in an interesting position when all the ground attacks started happening in the State, and the Guristas raid occurred. But because it didn't affect her personally, and she was too busy, it didn't give her a reason to change.
Had this occured during the time she (and I) would have been logged into the game, and she would have heard about this, she would have participated in the live event. Whether she would have assisted the State, tried to prevent or stop a fight, or backstabbed the other Caldari there and gone rogue for the Guristas, I don't know.
Whatever happens, happens.