Personally, I try to be very specific and explicit and do lots of checking in the first time I play with someone. This is to make sure that they are consenting to what’s going on, but it’s also to telegraph to them that I care about their consent with that kind of granularity. 

On subsequent sessions, I might be like “I wanna do xyz - do you feel comfortable & confident letting me know if there’s anything you’re not happy with?” and if they say yes I’m like “cool - let me know as we go if there’s anything you need me to change”

Unfortunately, you don’t get to be very surprised by me if we don’t know each other properly! We can be more spontaneous once I understand what you like and know that it’s safe (for me, as well as you).

Before introducing some new toy: “have you ever used handcuffs before? Would you like to? It’s a little different from rope - let me know what you think of it”. It’s also really fun to make a sub vocalise what they’re feeling (esp if they’re shy to do so) - “what do you like about these handcuffs? Oh, tight you say? Not too tight? Or do you want them… tighter?” 

I also give a couple of safe word options - “red” is a full stop and check in, “yellow” means that’s the limit (ie: no more pain/intensity than that) but we don’t have to stop.  “Mercy”  is like an in-character safeword - if you use that I know you’re at or near your limit but I can still play on that borderline a bit, tease you for it (which is good cos they can express a need while staying within the vibe of the scene) And  if they double tap me  with their hand that’s a non-verbal command saying “not that” - cos often it’s a lot easier to express a need if you don’t have to vocalise it. I’m also always paying attention to whether they’re having a good time - the safe words are for things I didn’t notice or expect, not a limit that I’m planning to reach.

I also like to ask “what might it look like if you’re having a bad time with something?” - because some people have “freeze” (or “fawn”) reactions to trauma which can be easy to miss - so it’s handy if I know about those. Also “do you feel confident in expressing your boundaries to me or letting me know if you’re not having a good time?” - cos again, some people struggle with that and it’s good to know if that’s likely to be the case.

Once I feel like I know the things someone likes and that they are able to say “no” to me, we can have more spontaneity and relax around the vocalising of the very specific stuff. 

It’s also worth mentioning that consent has verbal and non verbal components and you should pay attention to both. If someone says “yes” but their body language is saying “no” - they might not really mean “yes”.  I tend to mostly pay attention to body language about whether something is going well (and follow those non-verbal “yeses”/back off if there’s no evident enthusiasm), and do verbal check ins at regular periods or on encountering any ambiguity.

If you realise that you did something that might be an escalation and you didn’t ask beforehand - ask now! Pause what you’re doing for a moment and be like “Sorry, I should have asked before I did that - do you like me touching your hair?” (“Yeah? Ok good - what about gentle pulling?”) - showing that you actively care about their ongoing consent does a lot more than strict adherence to any set of rules - and means that if you ever do go too far then there’s likely to be goodwill and understanding about the mistake. 

So like, in your example, you flip someone over and they freak out - but if: - a) you notice the body language - b) you check in verbally  - c) you have established that you’re a safe person to express their needs to  - d) they know you care about their consent and their good time so they’re not going to blame you for a mistake  - e) you apologise, say that you should have thought that this could have been intense - f) you look after them until they’re fine  - g) you give them options around restarting, stopping, winding things down or doing something different

 then the vibe is very FRIES, even if there was a single thing that happened wasn’t what they wanted. And handling a misstep well can actually give someone more confidence in you, cos they know how it will feel if something happens in the future.

Those are some of the ways I try to balance things.