Idk if it works for everything, but here's what I tried. Check out outside and inside interiors and follow the process of level creation for my very first mod in REDkit for The Witcher 3 :)

00:00 Coming back to creating beauty
00:18 Your comment
00:37 Showcase of the results
00:52 Work with references
01:15 My concept
01:34 Building the creek area
02:30 A player will start here
03:34 Fences /borders
04:38 Tip 1 for beginners
05:29 Example with a skeleton
05:52 Tip 2 for beginners
06:51 Tip 3 An atmosphere and tone
07:39 Spawning area
08:10 Who has the same problem? :(
08:30 Tip 4. Put interior inside a house
09:30 Setting up a cosy bedroom
10:12 Change a degree of rotation
10:47 Some braziers have a sound of crackling fire
11:14 Tip 5. Organic touch
11:51 The front area of the house
12:41 Geralt checks my work
13:53 The next waterfall tutorial sneak peek
14:26 Have fun, play videogames :)