Write Outline
Before I start the outline, I make a folder for Supporting Characters and Worldbuilding elements. I also make a separate folder for each book and move the scenes for that book into the folder (making sure to keep them in order).
While I'm writing the outline, anytime I come across a new (supporting) character or a worldbuilding tidbit, I add a file for it. If I don't have a name right away, I use a filler and name the file the same filler name as the character. I only do a character sheet for other characters if they influence the main characters significantly (like friends or family members), or I feel this character might make other appearances in the story.
In Scrivener, I write the outline in the document view with the description of the scene in the side panel as a guide. This way, the outline is being written right into the same file as each scene. When I write the outline, I put the setting, basic action and dialogue for each scene. I write it like a screenplay, but without the formatting. It's extremely basic, but it makes writing the first draft so much easier. It also allows me to work out other kinks in the story before putting too much energy into writing the first draft.
I don't force myself to come up with names right away because it can mess with the flow of my thoughts as I'm writing the outline. I don't worry about the details for these elements either, unless it's something that comes to me on the spot.
My supporting character template and worldbuilding templates are below, and all are downloadable:
World Building Templates
Places
Worlds Template | Nations Template | Regions Template | Cities/Towns/Villages Template
Flora and Fauna
Creatures Template | Plantlife Template
Religion and Spirituality
Religions Template | Deities Template | Rituals/Ceremonies Template | Types of Magic Template
Technology and Resources
Technology/Weapons Template | Natural Resources Template