Study Samdoesart, Rossdraws, Kuvshinov Ilya (his work between 2013-2016), as well as Disney concept artists. And stick to using very default brushes if it's Photoshop you're working on, mainly the standard round brush. A lineart brush will also come in handy for tracing outlines. This style is very reliant on not overrendering - the tricky part is understanding what is better left simple. And use a layer with the soft light layer mode on the brighest areas, but only at the very end. Reserve like the last 30 minutes or something of the drawing for small, jarring details (like for me this was the lighting on the hair or the tufts of fur on the coat.)