Vidding Exercises for Creative Distraction

I'm gonna be real, I've literally never clipped as many people seem to do. And tbh my tagging usually breaks down well before I actually finish the vid. I've always imported my whole source to work with, separated by episode or by film. And then basically scroll back and forth through it 87 million times until a vid falls out? Even though I've had it explained to me I just can't really wrap my head around the process of like... pre-deciding things before the clips are laid out on the timeline? I mean, obviously I have some things in mind before I start, but not like what I've heard other people describe.