I write mostly about movies and I started writing my first reviews with a notepad inside the theater, making quick notes without looking as I notice something (just anything since it will be filtered later).
After four months I got confidence to just make quick notes on my brain and remember the more important ones in the final creditd. When it is write time, I dump a lot of ideas growing up with these notes.
This is my hobby so I am not interessed in spend too much time doing this (better watch another movie) so I force myself to write for every movie I watch and do it as quick as possible. The brute force is slowly improving my writing skills, do I am now more interessed in style guiding.