I strongly dislike green/yellow/red -- it feels too much like manipulating her through remote control. At least the green ("go harder") and yellow ("Don't go harder") do; red seems to operate like a standard issue safeword.

With dommes who are both new to me, and newer to the scene, I always give as an idea a protocol I enjoy that enhances communication (similar to stoplight) without breaking roles. It's just an idea I throw out that is totally her option, but a number of new-ish dommes have liked it. BAsically, it's:



Or, in other words, when I hit my very limit, I indicate this to her by saying something humiliating or doing something humiliating. This signals her the first few times, both what my pain limit is, and my facial and body expressions so she knows how to read me. It's not really "code words", but submissive words or actions, just used to communicate to her the first time "this is about my limit for intensity, and this is how I look and behave when I'm at that limit".