Great post, Betsy!!
I was reading through the comments (P.S. Thanks so much, Emma and Betsy!!) and I noticed Tonya's question about maybe having too many points of view in her current work-in-progress and if that could be why she's having trouble figuring out her story.
I've done both (only been published in first person, but I've written two unpublished books that will never see the light of the publication world in multiple POVs.). Honestly, I think it is easier to write in multiple POVs, but more natural for me to write in first person.
In first person writing, you can really get the voice of the character and develop that through the entire story. The storyline progresses with the character, so while it is easier to get "stuck" in certain scenes because you don't have that convenient "hey, this scene is going nowhere, so I'm going to just switch to the other character's POV". BUT, it is also very natural to add thoughts, ideas and backstory without it seeming weird, odd or awkward.
For third person and multiple POVs, you do have that convenience of switching scenes and people whenever the story starts to fall a little bit. But, you're right, Tonya, it can be hard to keep all of the individual storylines going! Plus, you've got the added challenge of keeping each character's voice unique from the others.
I think the best example of multiple POVs is actually in movie-form. Did y'all see Valentine's Day? Such a great example of how you can have TONS of points of view and still have a cohesive story that works them all together. Notice that no two characters were alike and every character had their own issues and problems. And notice too how seamlessly they all worked together.
If you're going to write in multiple POVs, I would recommend getting a journal out and writing out each character - names, descriptions, jobs, lives, etc and make a special note about quirks in their particular voice (like, for example, "Leonard's POV will include multiple sports references."). Be especially careful of bleed-through - don't allow the same voice to transfer to different characters.
As far as keeping all the ideas and plotlines straight, write them all down in that journal! I really think it's easier to write in a linear fashion - start in Chapter One and finish when you write "The End". But, y'all know me - I don't outline worth a flip. Another tip that might be helpful is to read back through your story every day before you start working. Back up to a point where you've written about all four characters and read through each of them before continuing, just to refresh your brain on each of their different storylines.
Hope this helps!! :)