I’d really love to see the finish product though. Do you have your sketches done?
I don’t know if this will be helpful but if you’re still trying to build your color pallette, i suggest going with the basic colors. When i was still using watercolor as my main medium, i have a pretty limited pallete but it still worked fine. Here’s the list of the paints i used:
You can also consider using Payne’s grey and some purple paint. They’re a pain in the butt to mix every time. Having ready to use tubes/pans will save you time.
Now, with the color pallete above, you can create a very wide range of colors. But if you want a more “sophisticated” color pallete, you can still downsize the list. I hope this helps.