I used to use the "stoplight" system for my safeword. When things were getting too heavy for me I would say "yellow" so Master would slow down. And I would use "red" when I wanted Him to stop immediately. For some reason I just didn't like that system. So W/we changed my safewords. Now when I want Him to slow down I will say the word "pity" or something like, "Please have pity on me, Master." If I need Him to stop immediately, I will say, "Mercy" or something like "Mercy, Master, mercy."
Master doesn't really have a long list of rules for me. He can be pretty lenient and lets me get away with things. But when He deems that I need to be punished He does it right then and there. It could be anything from a spanking to making me sit and not say a word to doing a chore that I hate. It all depends on the circumstance and His mood.