I create a different event sheet for each object with roughly the same structure.
I put the global variables that belong to this object at first, followed by a "startup group" whith all the stuff that has to be done with this object on start of layout or on creation
after that comes a movement group if its not static, followed by animation group etc.
I then include all the event sheets in a maingame eventsheet.
I also have a WIP (work in progress) event sheet where i can test new features and be messy with my code, once i feel the feature is complete and works how i want it to i can go ahead and transfer it all nice and clean over to the real codebase.
Also, use functions, functions, functions and if it's possible try to use local variables inside the function not globals outside.
that has not only the advantage that you dont have to reset the variables all the time,
but it also makes it easyer to copy the whole function from one place to another ...even from one c2 project to another
and you can use the same name for local variables over and over, that makes it easyer to pick names that make sense.
there's a bunch more, but thats what came to my mind right now,
cheers.