Switches and/or Self Switches would be my go-to in this instance, but knowing what sort of events you're talking about would help too.
For a one-time, self-contained event (like opening a chest) you can use self-switches--there are four of them available (A-D) and they affect only that one event. For example, when you open a chest, you'd have:
Event Page 1, with the closed chest graphic and no conditions:
Call Common Event: [Chest Open]
Show Text: You find 25 gold pennies!
Change Gold: +25
Control Self Switch [A] = ON
Event Page 2, with the open chest graphic, and the condition "When Self-Switch A is ON"
Leave the event commands blank here, or show text "The chest is empty."
This way, the chest will stay open and empty after you've interacted with it. No more infinite chests!
You can use self-switches for anything that's self-contained--if the change to the event is from an outside cause like a quest being started or finished, you'd use normal switches. For example, if you could only pick up party member Gloria after Aluxes is tasked with saving the world, Gloria's event would look like:
Page 1, no conditions, Gloria's graphic:
Show Text: "Aluxes, do you really think you're going to be asked to save the world?"
Page 2, If Switch "001: Save the World is ON", Gloria's graphic:
Show Text: "Someone really asked you to save the world?? I'd better come with you."
Change Party Member: Add Gloria
Control Switch: "002: Gloria Joins" is ON
Page 3, If Switch "002: Gloria Joins" is ON, no graphic
no event commands needed here!
That way, Gloria will not join you until you're asked to save the world, and she'll disappear off the map when she joins your party.
With more information about what you're trying to do, I can give you more tailored instructions--but by and large, Switches are the way to go for controlling when and how many times things happen.