In my time developing stuff, I've also made a few tutorials.
The ones listed here were even featured on YoYoGames official blog!
These might even give you a bit of an idea as to how I tend to code.
There are some others not listed here that I made for a Patreon a while ago including a networking setup. I may post them somewhere soon though.
My best guide seems to be the one for getting started in 3D in GMS2: https://forum.yoyogames.com/index.php?threads/guide-getting-started-with-3d-in-gms2-project-download.12145/
I also wrote a guide on setting up the camera system in GMS2:
I also did a basic one on room layers, but it's a little less involved: https://forum.yoyogames.com/index.php?threads/guide-getting-started-with-room-layers-mostly-new-gml-functions.13068/