Game Development workflow

Hi, I’m new in game development (i did some projects for training but nothing official),
I’m here to ask those who have some experience in game development about the main steps in creating a Game as I wanted start a project of an online game for PC/Mobile (yet to choose).

Basically I wanted to know which are the steps you usually follow in developing a game, like what do you do first after creating the project? do you create a custom online subsystem first or…?
It’d be nice if you could give me a list of steps/advices to follow or even some guides/pdf’s.

Thanks in advance!