Ever since I started using Sciverner, I created dozens of word document templates for anything I could need in world building. I have templates for the overall world (different templates for whether it is designated as a planet or a realm), templates for different sized land areas and settlements, for flora, fauna, landmarks, magic, weapons, regions, deities, organizations, character types, races, the list goes on and on (and I find myself adding new ones as needed).
Each template has all the information I need for a particular part of world building. With Sciverner, I can load the templates I need for a particular project, and then create documents off of them to fill out the details. With another feature of Sciverner, I can link details to other templates they relate too for easier access. It has honestly made the world building process monumentally easier. I still find myself tailoring the templates now and then for the specifics of a project, but having the outline is a huge help to start with. It is sort of like keeping journals for each item or topic, just digitally and organized alongside the project.
It might sound intimidating, but I only had to make the templates once, and now they are there every time I need them for a new project, or for similar items in the same project.
As for world building itself, I start with the basics, then let the rest evolve with the story. I update as I go to maintain continuity, but my world building process also varies slightly from project to project.
As a fantasy reader, I can say I also enjoy some descriptive world building in the story, although it doesn't have to be a substitute for plot. It is all about how the information is woven in. In Anne McCaffery's first Dragonriders of Pern book, I believe the first chapter starts with an in depth description of the planet Pern, the socioeconomics of the planet, the dragon riders, and some of the astrology of the solar system. It all happens before any characters are introduced. This method isn't used so much anymore, at least not that I see, but it works for her style and her world. Depending on the kind of fantasy/scifi you write may also dictate when and how you world building. Stories that overlap or take place in our world might require less building (unless it is an alternate history/timeline), because the world is already premade.