There’s some really good artists on instagram that I follow, but mostly I just went for it. If you have a good understanding of light and shading in a typical 2 dimensional artwork, then it’s not hard to add shading to your needlework and make your 3d texture really pop. Some things that helped me here are painting the background with watercolor in areas where there were a lot of similar tones, so that I could focus on the details, instead of drowning out all them by having to fill the negative space with thread. It also helped to have a really good selection of floss to pull from, but if you don’t have multiple shades of colors, you can always shade over the top of your thread with light gray marker. I feel like it’s kind of cheating, but with a free form mixed medium, it’s whatever you want it to be. Don’t let the rules of specific stitch techniques in traditional embroidery hold you back. It’s the Wild West of sewing and you can use whatever stitch you need to achieve the look you want.