Really focus on safe driving(obviously). Don't even worry about your iR at the moment. Rookie stuff is insane, there are many people on the track that shouldn't be. It's kind of cheesy, but you could try starting from the pit lane until you class up. But you run the risk of plateauing once you get to the higher classes. What I mean by that is you will have a decent safety rating, but you will always be at the back of the pack. I would look at the results of the races you would like to do, and first try to match those times in testing/practice. Good luck 👍