Blender

Use references, watch tutorials, follow them, don't listen to ppl saying not to do tuts, that advice is for people who have already used the software for yeaes and are stuck only doing tutorials, you'll only get good following ppl who know what they are doing ans getting good habits initially. I'm trying to hit 1 tut a day right now, still feel way behind from where I want to be 2 years in. If I didn't do any tuts id be so much further behind, just fiddling with sht cluelessly.

I think the purpose of light isn't to light up everything for readability but to grab attention or convey a message:

Here the victims are lighted by one source of light: the lamp. It grabs attention. we can read their faces. The white clothes that reflect a lot of light make the him a martyr or an angel. The shooters are in the shadows, dark and evil. The darkness makes them anonymous. The city is dark. there is no light in windows. It makes the viewer wonder what happened to people in the city. Are they asleep? Did they left? Or Were they killed?

Think of a light as a tool to highlight stuff and darkness to hide stuff.

As someone else said, use references. But my initial thoughts are that it looks a bit too flat, lighting that looks nice usually has at least some directionality. There aren't any shadows and a lot of the scene has fairly uniform lighting so possibly having a more intense light visible in the scene could help. If you're doing a render with a focus try to have some of the light directed to that focus (your little guy on the roof probably).

I will only suggest the absolute basic.

Look at references, lots of them
Find those renders and style that you like. Observe fine details and experiment to reproduce same result. If you don't understand how to do specific thing, you can always ask around.

Use real world scale
If you are not making stylized miniature render, model everything to scale. Same applies to light size and power. If it's too bright or too dark, fix it with render exposure or compositor.

Use HDRI
With Cycles, you get decent lighting in one step. And even though EEVEE resamples light texture down, it still have enough detail that gets you okay-ish lighting faster than multiple light object setup. EEVEE next already have automatic "fake sun" if you want that.

Have fun!

I think the window glow looks pretty good.

My suggestion is on the compositional side: The lighting on the humanoid lacks a physical source, so the highlight looks out of place as if the figure was composited into the scene separately. If you can think of an object that is casting light onto the humanoid and place it into the scene (a neon sign, light spilling from a rooftop access door, etc) everything would fit together just a bit better.

Another thing you could try is looking into 3-point lighting used in photography and film. Different 3-point configurations on the humanoid could help make them stand out from the background while keeping the highlights more subtle.

I have no advice, but the buildings look very Batman : The Animated Series, and it’s awesome.

I think it looks great. Are you using the Properties > Render > Light Paths > Bounces setting? Also, which render technique did you pick? Cycles or Eevee?

This guide and the rest of his channel is a great way to go from Blender novice to pro

1. Do bad lighting
2. Until you're not

I like to use the sky texture as its really easy to control Alternatively you could mimic it by adding a 2nd lower brightness sun light, turn the angle to 180° and change the colour to blue. This recreates the ambient light effect of the sky in daylight pretty nicely when paired with a lower angle sun light

HDRIs are also a really quick and easy way to get realistic lighting, although it can be tricky to get a sense of scale

Strategically placed glossy and metallic materials will help reflect light around your scene to highlight certain details

This looks pretty cool already!

You could give the windows an emissive texture, if you want to make it look more "realistic" or so. And add some fog to the scene. It's expensive to render, but may make it look nicer. Also check how to give the lights a "glow" around them.

As sibbo said, the windows might look nice with some glow, often called "bloom"