I'm pretty new at this but since I hate coding and despite of that I picked up something useful from object oriented programming class we had years back...
And that is... to group functions as entities. I accomplish this by using comments on my C2 events.
I also use global variable rather excessively since I use them very often to trigger events. I rarely have used local variables, however using local variables for hitpoints on an object was a great idea - since there could be more than one of the same object spawned and they would then have their own hit points.
So try to organize the events you have into groups that handle a specific function, for example spawning enemies, collision with objects, user input, game victory/lose conditions and so forth.
Also... if you ever duplicate your layout and want those objects to act differently than on the previous or other layouts... rename those objects so that if you modify their behaviour they won't get broken in the layout that it was copied from.