lines that define a contour are usually darkest. lines that define a convex corner or edge are lightest. black lines are good for separating thing, and for that reason can be overused, as in the interior of the building here. you should also choose a light source and shade one side of the building darker than the other.

could anyone help with the curved glass structure on the roof? I can't get it right no matter how many times I try

oh my gosh thank you so much...... this helps immensely. I don't know how I couldn't do it. Like no matter how much I tried to visualize the lines over a curved surface, the surface always seemed to look flat. I have a really hard time visualizing things, and curves in isometry can never be easy can they?
When I see an isometric piece of pixel art, it looks so simple, because with every shape I can practically visualize the designs just working within your ordinary isometric cube, but I just don't understand how to create various shapes and curvatures within that isometric cube.

thank you for cleaning up my letters and stuff up a bit too! I really feel bad about people doing things for me but I had to have attempted that curve glass structure for 3 hours with no success. I guess all I can do is study it, try to play with it to make different heights and curvatures, and add it to my list of minute things I can do lol. I can't thank you enough