What methods do you use to block out your map?

[Interfearance]

I am looking to gain insight on everyone's various methods of grayboxing/ blocking out their levels. What grid sizes do you stick to? How to you build corridors? At what point should two surfaces be separate brushes? Do you work from a sketch? What dev textures/lighting do you use? I am going to be blocking out my layout for the third time to lengthen rotation times and want to discover methods to create a clean graybox that is easily adaptable. Even the common mistakes of grayboxing would be helpful. I wouldn't post this if I had found some decent guides, but all of them are concerned on teaching the reader how to use the block tool and nothing more. If you find a good guide feel free to link that too!

[Apeyou]

I personally like to start with a little sketch, just to make it easier for myself to block things out, but after that it all comes down to playtesting. The thing I notice a lot with beginners is that their layout basically consists of random walls/blocks with no purpose. Try to think of what these blocks do, "is it a house, does it make sense to put a house there" etc. Blocking out a map is way easier if you already have a theme in mind.

[Interfearance]

Thank you for the help!