In dark mode, surfaces/layers should be brighter as they get “closer” to the viewer. This is the same as light mode interfaces.
Sometimes the rules of your interface in general can clash with either light mode or dark mode. For example, you might have a rule that important elements are always brighter, because then they’ll be noticed more easily. But you might also have a rule in your dark mode interface that elements are brighter when you hover over them.
You might find that these rules clash and what works in light mode doesn’t work in dark mode. Every interface has its own internal rules, so I cannot suggest a solution, but you should be aware of this as you work.
White text on a black background looks bigger to our eyes than the reverse. You may need to tweak your typography, for example, so that it looks the same weight as the light mode equivalent. This could involve a different typeface weight, more letter-spacing, or a less bright text colour.
Near-black looks more natural than pure black, which we rarely see in real life. Unless you have a good reason, do not use pure black. One reason often given to use pure black is that it allows some screen types to turn off their pixels completely, which saves power. I can find no evidence that it saves a noticeable amount of power. So it isn’t a good reason to use pure black.
The brightness difference between two dark colours needs to be higher than between two light colours to be noticed. For example, the difference between 100% and 98% brightness might be easy to notice. But the difference between 0% and 2% brightness might be impossible to notice. If you choose neutral colours for your background layers, the brightness difference should be higher in dark mode.
If you saturate your neutrals with a little colour, you will need to use more for dark neutrals than for light neutrals. While you might be able to add 3% colour to white, you may need to add 10% colour to black, for example.
Highly-saturated colours like accent colours stand out more against a dark background. If you want these colours to look the same to viewers, you may need to have two colour palettes. One for light mode, and one for dark mode. In their Human Interface Guidelines, for example, Apple provides light mode and dark mode colour palettes.
Because colours seem more colourful against a dark background, this makes dark mode a good idea if you want to use many accent colours.
Dark mode is more suited to lighting effects than shadow effects. Think of a glowing neon bulb. This makes more sense for a dark environment, based on our real-world experience. If you do want to shadow effects like drop shadows, they will need to be stronger so that viewers can see them.