No arbitrary intervention.
Only help with issues that players experience, fixing broken laws, getting that cart out of the deep ocean. All administrative actions based on written down rules in the ecopedia (or anywhere where players have a realistic chance to read them, no matter if they ultimately do) that need to specifiy what's going on. It's not really about the intervention itself, but the fact that players need to know when joining what's going on and what can happen. There is no reasonable beyond that, one server might have a lot of rules to facilitate a specific playstyle which gets interested players for that, another one might limit to action on griefers, getting players for that. Both are fine and reasonable, as long as players were able to be aware of what can happen and there is not suddenly the invention of a new rule or usage of the "this is my server, i decide what i want" trope.
No sudden rule changes and if so, not applicable to things that happened before. If a player does something you didn't see coming, that's not their fault. Not even when you have a feeling big parts of the server are unhappy with it. Establish neutrality. Players have a lot of options to deal with stuff beyond that themselves and for a fair experience it is necessary that pressure doesn't lead your administrative actions.
This is pretty simple and effective, but for some reason - not only in Eco - 80-90% of servers fail this test already. I get that people want to be the boss on their own paid servers, but you can be so while still being neutral and fair by just detailing what is going on and keeping to your own rules in every single case.
And yes, even that doesn't save from drama, as you might need some rules that are open to interpretation to catch edge cases or regulate specific things in a wider scope, given the document would otherwise be a very long law book, but try to define terms that are disputed (Griefing funnily means many different things to different people and can be from very clear cases to a wide array of anything that is 'meh'), develop the rules with your community, adjust them after cycles and yes, live with the occasional "You're free to go, despite I hate what you did" and any pressure you might get for that. In the long run, as of my experience, that works out much better and gives you a reputation that will help you for interpretational cases, given you built up trust.
You keep ownership of the server, staying in charge, being able to build the kind of community you want, but give players the - in my opinion - very basic respect of them being fully informed and knowing if they want to use their time on this server based on your rules.