I think your topic would be better in other section , but since you asked, I’ll answer…
Something that helps a lot, even without understanding much about anatomy, is to try to see living beings and objects in a three-dimensional way… like I did with this arm (1). In one layer I traced the contours and, above, I drew the lines in blue. In this topic, there is a tutorial explaining this layering method.
So, notice that the lines are curved (even those that seem straight have a subtle curvature). Someone else might draw with even greater curvatures than I did.
I drew the clothes and other elements (2) and redid the drawing in (3). In (2) the folds of the clothes, the ornaments and the bands are very straight. In (3) I traced them with three-dimensional shapes in mind.
The sleeve (a) looks more convincing if it has a certain curvature and if you trace it in a way that gives the impression that the fabric has some thickness (see the red arrows).
For the decorations, it helps if you draw an ellipse diagram (b). As for the arm bands, I couldn’t draw them very well. In this case, it might be better to use a photographic reference to see what they look like in reality.