My process is to build the world before I build the characters. I do this because I want the world to be important to the lore just as much as the characters are, especially for fictional worlds. Since lorebooks are a thing now, I want to rework my old series as well because so much information was left out due to token space, but I don't have to do that anymore. The only tip I have is don't be afraid to get creative in world-building. You can overdo it. Don't hinder your imagination. Let it run and sprint free. In my opinion, that's the best part of it. It's the most fun, too.