I usually make a flow chart of events that I want to see happen. Also helps with paths if you're trying to do a story-game. That way you can see/ fit together the events. The way I work through writing is that you have to get through the slog of the boring parts to get to the parts you want to write. For me, I hate writing action sequences. I hate writing combat - but I do enjoy writing dialogue. So I know I'm going to struggle with getting through action bits, but my reward for slogging through is writing my favorite part. Its a give-and-take relationship.
As for short stories, I usually set some guidelines for them. I usually cap my short stories around 2k words. Then I word vomit all over Word. Once I have it all on paper, I go through and cut out all the nonsense that doesn't contribute to the story I'm telling. Edit and boom you get a focused, cleanly written short story.
The best advice I can give for writer's block is taking a break from the main piece your writing. Maybe write a shorter story set in that world, but not necessarily apart of that main story. It helps with world building and can give your audience an opporunity to see into the world you're building and get hype about it.