The great thing about having “cool parts” and “great/important scenes” in your head from the beginning is twofold:
1.) Having something cool to work toward will get you to sit down and write! Good to have something to look forward to in a loooong race. :)
2.) You recognize what makes a scene cool/great – which means that you can use some of those elements in other scenes. A book shouldn’t be a lot of boring stuff and then a few great scenes – every scene can be great, or at least interesting. So when you find yourself writing something that’s boring to you, stretch your brain to try and figure out how you can make it more exciting or insightful, using your “good” parts as inspiration. Can you add a cute character moment? A running joke? A surprise? An interesting setting? If the scene isn’t interesting to you, it may not be interesting to your reader, either. O.O
You mention you’ve finished Beyond Beauty – that’s awesome! Do you mean you’ve scripted it all out for Scotty? This might be a topic for another thread, but I’d be very interested to hear how you work with Scotty as a writer/artist pair for a comic, since Beyond Beauty has a nice harmony between its art and writing. A lot of creative pairs can’t pull that off.