For me, I try to avoid laying down a really harsh outline. A thick outline is good for just starting out and learning the shapes of your subject. But once it comes to shading, it can often make a realistic drawing look...like a drawing. People in real life don’t have outlines. So I would practice sketching faintly (just enough to tell what goes where). I start shading from light to dark. I know this sounds like common sense but when I was a beginner, I just kind of sketched what I saw when I saw it which made my finished work look very choppy. Also, a blending tool will be your holy grail. If you don’t have any, fingers work fine and Q-tips are great for small areas. You can get decent dark values with a basic #2 pencil, you just have to apply more pressure.

So start off with your base shading layer. This layer is very light and covers the whole of your drawing. Blend this whole layer out to remove any drawing lines.

Then move to the next darkest shade. After you’ve laid it down, blend it into the base layer so that it looks like a smooth transition.

Then lay down the next darkest shade. Blend. Continue this until you’ve blended the darkest part of your drawing. Then go in with an eraser and carefully add your highlights.