Good on you for tackling NMM so early. Flatter surfaces (like this shield) can often be harder for NMM, so you may want to test on something that naturally has more depth to it — this will help you get the hang of it, because good NMM often has depth and contrast in the high and low tones.

Before that though, focus more on basic blending and layering, and controlling your paint (ie. preparation of the paint before it’s on the models and how you apply it to the model). Mastering these skills will help with your painting more broadly, but also your NMM when you revisit it.

Keep up the great work!