I am seeking examples of clean ways to transition from my main characters to my secondary characters. When I review what I have written, it is clunky and unclear that the story is now focusing on the secondary characters, and this causes confusion.
The reader does not need to know "the story is now focusing on the secondary characters" - that's meta information for you, not for them. You are focusing on the secondary characters for a reason -- perhaps as a way to fill in the main character's backstory (by having the secondaries discuss it without the main around), perhaps to move the plot forward (by having them do things that will eventually affect the main) or whatever.
There are two ways you can do it. The first is to give one of the secondaries a scene with the main, and then follow with a scene featuring that same secondary and no main. That's generally pretty straightforward. The second is to just "cut" to a scene that has no people in it who we have already met. This is a little mysterious. You can either signpost things to help the reader, say by having the people discuss the main and establish the relationships in the first few paragraphs, or you can lean into it and be mysterious, maybe not even giving the secondaries names at first. With an omniscient narrator, you can do things like:
Sue [the main, who we've been following for chapters] had no way of knowing her plans were about to be completely upended. In an apartment nearby, two young women sat at a dining table. Papers were everywhere. Pushing her curly hair back for the thousandth time, Ellen sighed deeply. [now some expository dialog in which Ellen can call the other woman by name so we know who she is, and what they're up to.]
How much you say "and now for something completely different" and how much you sort of slide from "these pages were all main, these were main and secondaries together, and these are all secondaries" is up to you. They are all valid ways to change your focus for a while.
You're asking how to transition between main and secondary characters.
Before I begin, let's talk shortly about first drafts. They're always stinkers and even your favorite author cannot write good first drafts. The most common fix is to not worry, keep going and fix everything in editing. Editing is when the "real" work of finishing the novel begins... kind of.
However, sometimes a problem with the first draft prevents us from continuing to write. We feel the problem is so big it can't be postponed to editing, but rather needs to be solved right now.
Sure, you'll have to fix those clunky transitions sometime, but it doesn't necessarily have to be before you finish the first draft. That's up to you to decide.
If your question means how to switch point of view (POV) or perspective from main to secondary characters, I suggest you look into perspectives. What perspective you use will determine how these transitions can be done. In most of them, a good strategy is to stay in one character's POV for a whole scene or even a whole chapter and to always be clear with what character's POV we're in, usually by naming the character in the first paragraph, unless they have a very distinctive voice.
If your main character and your secondary characters all have POVs, you may want to read up on how to do more than one POV character. This subject is huge, but what POVs a story has could depend on what info is needed and who knows it, to if you want a sprawling story with many perspectives or a narrow story with only one.
Perspective, Scenes, Perspective...
I determine POV characters by combining a few notions:
- The character with the most to lose in a scene should have POV in that scene
- From your story and your POV characters you can sketch up a list of "most to lose" scenes
- By focusing or widening the story you can remove or add POVs, and similarly, by narrowing or widening the cast you can add or remove scenes (or turn them into transports/sequels—you usually do this for scenes where the POV character isn't the one with the most to lose; we selfishly skip other people's problems to focus back on our own...)
This is an iterative process you can tweak back and forth until you have a cast and a set of scenes that seem to match other criteria for your story (like what you want to say!) You'll never have a perfect list, but that's fine.
If transition means focus in general you're free to focus on what you want in the story. However, perspective will inform how to best do this focusing (e.g. can the POV character see or know what you focus on? Or is the POV not limited by one person's knowledge?)
Chapters & Scenes
As you may have picked up, you use chapters and scenes as general building blocks in your story, so they also become the general tools for focus and transitions. Transitioning between POVs, Timelines, etc. becomes a question of transitioning between chapters and scenes.
To keep your scenes distinct they should have a single POV character (scene protagonist) with a scene goal they are striving to achieve, but they meet resistance (from a scene antagonist) usually leading to the scene ending in some form of smaller or larger catastrophe.
Incidentally, in creative writing things like location and cast are way less important than they are in stage- and screenplays (where sloppy handling of these might have people running on and off stage like rabid rabbits... not to mention the risk of creating unplayable location transitions...)
You then string scenes together with "therefore" or "but" (rather than "and then"). I.e. do "John wants to marry Jane but Jane loves Luke" rather than "John wants to marry Jane and then they eat wedding cake..." The first form is usually crucial to create catastrophic scene endings (the two are different perspectives on the same thing—creating a story with conflict).