I think what’s important to understand is that drawing is fundamentally different than rendering: with drawing lines, it’s much more binary. By that, I mean that with lines, you are only given basically black and white to use, so you have to be selective about which lines you choose to represent. Lines don’t exist in real life, only changes in value and color, which are simplified and abstracted when you draw lines to represent those value changes.
So, when you are drawing, you have to choose what lines are most important, and which ones are not. Facial creases are generally quite fine details, so depending on the complexity of your piece, I would advise to ignore them or be very careful, and use a light line weight. Also, don’t try to go too far into “this is a cheek, so I need to draw a line for the cheek here.” Just focus on areas of contrast and representing tonal differences with your lines.
A good way to judge whether or not you should include such lines is to try to blur your eyes while looking at a reference. If you can still tell apart the difference between tones, draw a line. If not, ignore it.
I know that’s a wordy explanation so here it is visually on one of my current WIPs (hoseok :D) This is a good exampling because he’s smiling so widely, there’s a lot of creases appearing on his face.
You can see I still chose to include certain details like his dimple and his double eyelid folds. Because I could still clearly see his under-eye bags and a bit of his cheeks, I drew those in lightly.
The same thing applies when you are painting, just be very careful in your contrast. Chances are, you’re painting the creases too dark. It doesn’t take much of a darker shade to get the job done.
Notice how I chose to omit the lines when I started shading. This illustrates what I was talking about earlier- the shift from line drawing to tone rendering. Had I kept the lines, the black lines against the soft grey of the skin would read too dark, and started looking like the example on the left again.
This concept can apply to a lot of details in general (teeth, clothing textures, and fingernails are common things I see people struggle with ), not just facial creases. So I hope this helps!