Some general advice that starts with a question:
How long do you think it might take you to write an Asteroids clone? Handful of asteroids floating around on the screen, wrap at the edges, ship that can rotate, fly, and fire on them causing them to split into smaller asteroids. Keep score.
If you have the experience to write a more complicated game then the answer should be on the order of 4 to 8 hours tops. (I wrote my Asteroid Panic asteroids clone in about 6 hours but I was also trying to use an entity system and make a good open source example… the art took longer than the coding.)
Every single thing (every one) that you learn when making something simple like that is 100% applicable to a more complicated game. So if the simple asteroids clone would take you weeks to write then imagine how much trouble the more complicated bits will take.
This is why we recommend people start at the shallow end of the pool.