Bedrockgames
I post in the voice of Christopher Walken
Thats the nut to crack. A lot of folks are uncomfortable with an evil character like an assassin. Or the idea that an evil character has to kick every puppy and steal every babies' candy or turn in their evil card. Additionally, you have folks that think every action works like a meta math problem. Every time you slaughter babies, you can just donate to an orphanage to balance out kind of thing.
Of course, there are also make the paladin fall type GMs that place trolley dilemmas into every adventure. When I run 3E/PF1 I have players consider what alignment they want to select and then im fairly hands off. An obvious pattern needs to arise before I as GM step in. Like a good character with a taste for torture and killing. That wont hold up. However, I dont force changes for trying moments that a player has to deal with. Doing something very much out of alignment could be a great RP moment. Is this the turning point of a new arch for the character? Or maybe its just one of their darkest days? Perhaps an epihany that changes their life? I put that in the player's hands and alignment can be a great guide for such occasions.
Otherwise, whatever you pick and stick with will follow you. Probably 60-75% of the time it isnt going to matter. Though, sooner or later planar war spills over and you are likely to find yourself effected by traps, spells, weaponry designed to target folks of certain alignment.
In Ravenloft they eventually quantified evil actions for making powers checks (which were pretty fundamental to the setting). I didn't agree with all the choices they made (for example, torture is still torture regardless of how you are using it against in my mind). But this chart was actually handy for handling some of those Paladin questions if you needed a hard and fast answer in the AD&D alignment system: I still tended to prefer the more open approach prior to this chart but I did often find this one useful):