Apprehension and surprise in a scene

[Ranai]

One feature of a scene is the fine art of balance between sly planning and joyful improvisation.

Another question is how much the person at the bottom is told, or guesses, of what is going to happen.

The expected: build anticipation. :SHOCKED:
The unexpected: surprise party. :vampbat:

For those of you with experience on the top...
How do you build apprehension or anticipation in a scene?
When do you prefer to keep your submissive in ignorance until the moment arrives?
Have you laid out a selection of tools 'Eenie, meenie, minie, mo...' ?
Have you told them to choose between Scylla (flogger) and Charybdis (crop) ?
Do you keep him/her waiting... naked, blindfolded, kneeling on the floor?
Have you secured your submissive spread open and helpless, to open a mysterious box before their eyes 'Here's my new torture device...'

For those of you who have bottoming experience...
Have you been told in grim detail what 'horrors' awaited you?
Have you experienced scenes where you had a vague idea what was going to happen to you, but not how?
Have you been kept in limbo dreading the unknown?
Has your Dom/Domme sprung 'nasty' surprises on you?
What do you like about hearing of your imminent 'ordeal'?
What do you like about being kept in the dark?

For those of you with not much experience (like me)...
Your clever ideas for apprehension buildup & surprise engineering?