I think this is a very good first build. Good job for sticking with it!
Feedback and Questions
-I love the use of those ads, you paid very good attention to detail 
-The textures of brick and concrete are not sitting well with me. I’d play around with textures a little bit more.
-is there an interior?
This made me laugh
Good reference material and tips:
Google and Pintrest is your friend when it comes to reference material. Don’t rush the building process! If you want nice looking, high quality builds then spend as much time as you can on it.
From the forum:
Mess around with Blender. It’s really hard when you first start out but youtube has many tutorials out there to get you started.
And plugins are your friend!!
Archimedes 2 and F3X etc…
plugins
List of top 10 plugins (Note: not all building plugins)
Top 10 Best Plugins On Roblox. Exactly as the tile says, in this post… | by Molegul | Medium
Also, mess around with different genres, get good at building different things.
Hope this helps!
Sincerely,
LandofLee1620