hello @faisalhussein394 :)))
I very much like your style; honestly, it's a joy to read your comic. I think I once wrote to you that your style reminds me of older comics I loved to read when younger; I was missing seeing it, and finding your work is like finding the best jewel, haha.
And, to join the topic, so two things:
I very much like to outline, and then I use a thick black line. I rarely share these sketches on Tapas, but that's one of my 'signatures'
Like this:


And the other is smudges. When I started to draw, years ago, I chose oil pastels (nod dry) and liked to smudge them with my finger. Digital tools have this as an option, and honestly, I abuse it. So, I first draw harsh lines, etc and then for hours I smudge them until I have this effect:

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