k so I always find it helpful when I'm shading a yellow object to make the shadow a little bit orange. idk, it's just something fun to try! also when u add highlights, try doing the soft airbrush thing and then putting a little hardedged accent, it makes things pop. ( thanks for indulging me, I hope this is helpful, also take everything I say with a grain of salt, I'm still figuring things out XD)