#1 - Driver mod (seat time).
If you want to get into actual racing, doing autocross... don't touch a thing. Learn the sport, learn your car. When you can't improve your time any further with the car as is, start making small incremental changes.
At that point, then follow the recommendations of @
cjd and do alignment and tires.
The stock car handles very, very well and you would be wise to just go out and learn how to
drive it well as it as is.