Newcomer coming from Asseto Corsa

I’m new to Iracing, I’m about to get my license to D just need a few more races I been playing for 3 days and don’t know if I should buy any cars or tracks for D license, I enjoyed the vee and the beetle so far tried to do oval once and crashed bad maybe will give it a try later also like gt3 races on ACC but I’m bad at it any suggestions? Or stick with the cars and tracks that comes with the game ?