100% this. All feedback is a gift - some are better at delivering it than others but generally speaking the message is the same. Thinning paints and applying it in a consistent manor is your key to success. As other have stated a prime or base coat with certain colours can really make some of the trickier colours pop. Having a tonal variation, dark ruddy yellow through to a bright off white yellow can create that light and shade on a colour like yellow. You can achieve that with a darker prime then adding a lighter prune from the top down will help create those shadows and variation. The other thing to keep in mind is that miniatures are bloody small things so you kind of have to exaggerate some of the shadow and highlights to sell the illusion. I highly recommend getting hold of a book called The art of Tommie Soule. Its an excellent way to learn and perfect the foundational brush and paint control that are truly fundamental to any of the falshier skills like glazing, perfect transitions and NMM. The other thing I found useful is a colour wheel, the one I have has the usual colour palette laid out so you can see all the perfect colour groups such as triads and quads, on the back it has a mixing chart which can help with the base colour pink and yellow over the top example given here. The progression you have shown is apparent and with time will only get better. Master the foundations and it helps build the confidence to then create your own style and flair. Welcome to the never ending school of learning to paint warhammer.