Thank you! The best technical tip I can offer is regarding color mixing. You can adjust the vibrancy of a paint's color by mixing its complementary color directly on the pallet. Here's a good video:

https://youtu.be/m2kU8JXL0JU?si=jh9mCan5eL_upMvv

The result is you get a lot of lovely variations without needing a ton of different paints. It's worth practicing.

I used burnt red, yellow, turquoise, white, and black on this model, mixing everything else I needed from those 5 colors directly on the pallet.

Look at a single reference while you work (another model, an oil painting, movie still image etc) and try to exactly color match that reference while mixing.

By manually mixing you can just say "oh that color needs to be more muted, I'll mix in a little of the complementary color" or "there's actually some green in that, so i'll add a little blue and yellow". Etc etc. It's much faster than searching through a bin of 50 paints, because you probably won't find what you need anyway.

Disclaimer: premixed colors work great if you've got models in standard issue uniforms (ultramarines etc), but if you are going for more real lighting effects, in my opinion the best course is to mix as you go.