Lighting is a very important step in order to make the area that you build feel real and atmospheric by the player, if this step is not done properly. You could have the best models and structure design in the world, but without good lighting, none of that can be utilized.
Additionally, from the given screenshots, you seem like that you are able to work your way around the brush tool and how to edit Vertexes and such. But in reality we don't really "detail" with brushes, they are only used to put down basic walls, floors and ceilings. Sometimes we have to use brushes to reach the detail that we need, but that usually then gets turned into models or func_detail.
Optimization is a big topic here, as we always play near the limits of what we can put into a map, so knowing how to use as fewer brushes as possible, knowing how to not overdo it is an important factor. Alongside this there is a lot of other stuff too, like Visleaf optimization done through hint/skip, Areaportals to precisely optimize key areas, using Static Prop Combine to merge props together in areas to reduce draw calls, compressing textures to reduce possible stuttering and much more. Not that you need to know all of this, but hint/skip and Areaportal usage is something that needs to be mastered, at least here, since we try to optimize everything as much as possible.