For the film, none. I would assume anyone coming here has seen it or knows enough about what happens. For things like Rebels or any new material, I would say maybe for a week after include a warning at the beginning for actual spoilers? If it is just a speculation no warnings are necessary.

If writers/prompt OP wants to include warning it is up to them. But I will not enforce any "spoilers" policies at the time being.

If people do want them I'm happy to listen to your ideas on the matter.