My writing process is a mix of the pre-planning and 'seat of the pants' methodologies. I do some work beforehand, laying out some general waypoints, researching topics likely to come up in my writing, and getting to know all of the major and minor characters in the book. Once I've done that, I have a general map of where I want the book to go, but don't actually know how I'll get there; that happens in my daily writing session.
I try to write 1500 to 2500 words per day, when I'm actively writing, and generally write in a linear fashion (from the beginning of the story to the end, without skipping around). Each morning before I start, I look briefly at my pre-planning workbook, as well as the writing I did the day before; this taken care of, I start typing, and let the story spill out of my head and into my laptop.
The reason that this works for me is that I know the situation and the characters...given that...my sub-conscious takes over a bit, and I let the characters write the story. A key to this process is knowing a lot about my characters.
I fill one of these out for every character with a speaking part in my books, and it forces me to really get to know them before I start writing. One of the perennial items in the "Additional Notes" section is the name (or names) of people that I know IRL that share traits or personality or features or aspects with the character.
I was working on these character profiles yesterday, having fun getting to know the new ones, and having fun getting reacquainted with the regulars, when it occurred to me that these aren't so different from the ones that I used when I played D&D a million years ago.
The character profiles I use for writing my books, and the character sheets that I used for D&D serve much the same purpose: to help create a fiction by aiding with the suspension of disbelief with believable details. Knowing about your characters helps you to tell a better story.
I often get into discussions with beta-reading minions about how or why one of my characters would act or react in a given situation, and I can generally answer...because I know...I know their family background and job history and favorite foods and their pets' names.
That stuff doesn't need to (in most cases it shouldn't) make it into my stories, but it's worth knowing, because it makes the characters more real to me...which will hopefully make them more real to you.