It's ironic that all the necessary precautions to planning something like this can have a detrimental effect on the nature of the event. If role-play is being assigned and discussed and you have to cover all the safety aspects whilst explaining what you want to happen and how you want it to happen, all the details can turn into a porn film plot and you risk losing the spontaneity, the excitement and the thrill.
So again and again with the trusting... To fulfill a Ravishment fantasy, you want to be able to do it with someone who knows you well enough to be able to understand your desires without you having to spell absolutely everything out so that there's room for a basic scenario and plenty of improvisation. And you need to be able to trust that person not to take things too far and to stop absolutely if you use the safe word. They also have to trust in you, that you know yourself well enough not to let them push the limits to a point where you'll regret it and will then blame them if anything goes wrong.
Protip: don't go ravishing strangers.
I make this sound all so complicated and with so much to consider but at the end of the day, two-way communication beforehand is the best possible way to prevent unpleasantness occurring.
This is why I recommended that beginners start very tame. The better you know your partner, the less it needs to be "scripted" as you pointed out. By starting tame and building from there, you'll learn from one another and build that trust that makes scripting or elaborate agreements unnecessary. The man who suggested jumping right into a very advanced role playing scenario immediately the very first time would encounter huge problems that wouldn't arise if he started with a very tame scenario with his partner that became more and more elaborate over time, as the two of them learn what pleases both of them and what works for them.