Well design itself is the framework of everything in it. Most designers create a design document if they have an idea for a game and are committed to it. This document is the blueprint for everything, from game engine, programming language, genre, maximum number of players, game mechanics, goals, level of difficulty, etc. The idea is to not stray away from the design document you created, but try to stay as true to it as possible; if it's unfeasable or unfun, drop it or modify it. After drafting your first design document, your next steps is to figure out how how you're gonna try to stick close to it. If you have an artstyle in mind, how will you integrate the graphics? Can you program the game mechanic in? Can you compose music to set the scene? Or you can hire people to do so (but that is very costly).
Oh and last thing, unless you know you can, don't make it a full time job. The amount of people who drop everything to make a game of their own is staggeringly high, and the success stories is very, very low. For every Undertale or Cuphead, there's 100 more indie games that never see a peep. Keep it a hobby.