Hi Victoria,
You've already gotten some great advice here.
I wanted to echo what everyone else said about it being the execution that counts. The formula that Jody refers to has a proven track record for working in PBs. This isn't to say that if you do A, B, and C, you'll automatically have an amazing PB. It takes so many more variables to make that PB stand out. As Mindy says, this is just the bare bones of it to get that first draft down which imo is always the hardest.
Interviewing your characters is another great way! I've done that often. As is Alan's suggestion for using mentor texts.
Page breaks and pacing are also key factors in PBs. I find myself looking for rhythm whether it's a rhymer or not, every PB still has a rhythm that keeps the book flowing and the reader wanting to turn to the next page.
While it is true that not all PBs use the 'rule of three' formula and not all PBs even have a huge defining conflict, there still has to be a certain 'main character needs to do this and how does he get from A to Z' in every book to make it work.
For example: In Race Car Dreams, Race Car doesn't really have a problem per se, he's simply sleepy and prepares for bed. From point A he's at the race track, by point Z, he's taken his bath, filled up with oil, and reads his book, (see still kind of the rule of three---not attempts and fails, but it's still there) and is finally snoring and dreaming. Many other quiet books follow this pattern too.
The example Alan gives is a great one. I love that book btw! Josh is a master rhymer! I've found that when I first start creating a new book that mentor texts are SO helpful. And yes! I do usually choose three that have the rhythm and pace that I want for mine. I'll read them over and over and study them. Then, once I have the rhythm I want to use (which is usually a combo of the three or an entirely different one) I let the idea mull around in my head for days, or even weeks. I write down thoughts I have. Lines that stand out that I hope to include. And any character flaws, quirks, or conflicts that need to go in the book. THEN I start on my first draft. Which is usually pretty stinky.

But! It's solid words written down for me to mold into a book. And yep! What Mindy says, those critique partners are golden.
Oh! one last thing. Tara Lazar also has a great blog post about Picture Book Dummies. You don't have to be an illustrator to create a dummy. Dummies are fantastic in helping you with pacing and page turns.
https://taralazar.com/2009/02/22/picture-book-construction-know-your-layout/Hope this helps! And
