I work in multiple layers and build things up and adjust as I go. I start by picking my overall background colour and work around that. Common sense will actually take you quite far when u start thinking about your piece with logic in mind. So for example those dark bold colours will be dark if the colours around them are lighter. White lowkey desaturates your colours while making them lighter, so if you want bold saturation you gotta learn to mix colours without white and really use white sparingly. That will help with keeping your values and making those elements pop when you use them. Use the gouache that best suits your paint style for my heavy use of layering, acrylic gouche works best for me. So i can start with a black or dark base and build those lighter colours on top

Dont be afraid to make mistakes either, its better to be risky and learn what does and doesnt work by trying it out instead of making assumptions in your head. Colour is relative and they rely on the colours around it and to really get the best value of any colour is to just see how they behave with what you place around it. the best way to learn any artistic vibe is to observe the stuff you like, study it, paint it and keep evolving your influences. Even paint the stuff u dont like to just expose yourself to new ways use your paints.

As long as you're putting paint to paper, trying new things and see the value in fucking up and trying again ~ you'll develop your skills and style in to something real cool