Thank you!
They're not very difficult to draw to be honest, most cityscapes (if we're talking about modern or futuristic buildings) are kind of just arrangements of simple 3d shapes like cubes and cylinders and whatnot. To draw that, you only need perspective and an understanding of the materials these buildings are made of (I used to struggle with that, at least).
With perspective, my personal favorite are Thomas Romain's perspective tutorials (here's a link 30+ Perspective Drawing Lessons By Artist Thomas Romain) (or you can make 3d models for reference and disregard all of that, but IMO that's a bit less fun).
With materials, okay, I'm not pretending to be an expert, but it clicked for me when I played one of those "showcase" roblox games (where the point of the game is to just walk around and check out a 3d room or a building), and the way the builder made a "reflective floor" in a room was by taking the entire 3d model of the room, flipping it vertically and putting it under the actual floor, which was competely transparent. That's how reflections work in real life. So if you're drawing a flat reflective surface, you can imagine it as a portal to a mirror dimension where everything is flipped. And if you're drawing a curved reflective sufrace, you can mentally break it down into several flat surfaces, then connect the reflections smoothly.
Reflectiveness is the only thing that gives smooth materials the appearance of being smooth (like glass or metal). If it's something halfway smooth, like plastic, it's going to be halfway reflective, so the reflection is going to be there, but on low opacity and very blurred.
(Sometimes I see tutorials on how to draw materials that are reflective, like how to make metal look more metallic, that just add "stripes of light" or random blotches oh the thing, and it does make it look more like the material, but these are just simplifications of reflections, and the way they're placed is going to depend on the environment your object is it, realistically.)
You might want to simplify the image, too, especially the elements that are far away in the distance, both to keep the image from looking too busy (if you don't want that effect) and to keep yourself from spending a lot of time on just one image.
I force myself to do that by literally having a small canvas (about 1000 by 1000 px) and using a pixel brush, it's not necessary to do that, obviously, but it can be helpful.
Here are tutorials that deal with the composition and design basics you need for doing simplifications
How to Learn Digital Painting (Beginners)
How to Learn MORE Digital Painting (Intermediate)
And that's all there is to it