@SaherYosry Nice sketch. I agree with what everybody is saying here.
Sometimes I find that Photoshop and other apps/programs, can be a little too much for me. I've always loved traditional media, and when I use digital as a tool, I just want to draw and paint. I don't wanna use all these other things.
But, that's just me!
However, artists have used little tricks and small steps to help them accomplish their goals when working on their masterpieces.
Like grabbing a HB pencil(or any pencil, etc), and a piece of paper, and doing thumbnail sketches, of your sketch, exactly the way you have it there. And then do more.
Just quick doodles.
Also as small value studies.
And try different things.
Have fun experimenting.