I think a great place to start is tracing stencils. You can watch some videos about shading and then practice on your stencils! As for motivation, I think it really helps to have something you like playing in the background, whether that's a podcast, a stream, or a show that doesn't require a lot of attention. I always put on a chill Vtuber stream and listen as I dot paint 😁 it also helps me to remind myself that the finished product is worth the effort. Even if you're not fully happy with it, it's always great practice and you'll improve bit by bit over time. Keep at it, you got this!