Oh, that sad little stack of scenes. Not enough ideas to make a story, but the original thought that sparked the idea of it is just too good to let go.
I have so many of these! The main issue with these is that they need to be written to see if further ideas can be built on the original idea. An actual outline might, or might not, be useful here. I tend to deal with these stories in one of two ways.
On the one hand, I can pants it. For these, a full outline isn’t the goal. Because the idea isn’t too big, these are going to be short stories or even just a few scenes, something for a bigger idea to glom onto. I did a bit of this last NaNo, with limited success; I got several scenes written, but there hasn’t been a single epiphany about where to take any of those stories next.
On the other hand, I can try and force an outline. Rather than letting the story fester in my imagination till an entire storyline emerges, organic and whole, I take a hard look at what I have, add depth to characters, goals, and give them an end point to reach out for.
Needless to say, this second choice is a lot more work. But isn’t that the primary skill-set of a writer? It’s not enough to know grammar and phrasing, to know how to take the pictures in my head and put them onto paper. I also have to be willing to build a structure that will carry my characters in challenging directions.
I think that if I had a stronger internal grasp of various plot arcs and narrative flow, I’d be better at pantsing. Plus, I’m not always pleased with the particular tropes and ideas that I fall back on when I pants. A little bit of random writing is fine, but I’ll never finish anything that way. So as appealing as it is to dash out a few scenes, I’m better off if I stick to plotting and craftwork. Dammit.