Assuming clip B follows clip A, what is the proper way of adding a fade to black at the end of the first clip and fade from black at the beginning of the second clip?
When on the Cut tab I try to drop the Dip to Color Dissolve effect, DaVinci Resolve automatically selects the joining, thus both clips. I have to separate the clips in order to add fade in-out separately to both clips.
In other words, DaVinci Resolve automatically assumes cross-dissolve, which in turns requires an overlap between both clips, which doesn't really makes sense when I am fading in to black and out of black.
There's no one 'proper' way. There are many ways to get that result.
BMD just released an updated Beginner's Guide for version 17. That guide covers basics like this pretty well. It's a great way to get started with Resolve.