I'm relatively new in the racing scene. My nearest track is is some 140km away and I need to travel by public transport. In short, I can't just go the track and practice a bit.
What I do is go to as many races as possible. It's more fun than practicing on your own (imo), you have other people as a reference point, both for setup and trying to keep up.
Also, decide what you you exactly want to improve and focus on. You can focus on your driving skill and setting up the car, but it's a lot to do at once.
I for example often just find a setup that kind of works (because with my *cough cough* refined driving I get such faster lap times with the smallest of setup changes/improvement)
Then I drive the car as much as possible when I'm at an event. For me, driving skill is not just being able to go fast consistently, it's also being able to adapt to your car and maximize your performance when the setup is not the way you'd like. After all even with experience in setting up your car you'll sometimes hit problems finding the right setup. This is where other racers might be able to help you (quickly), however for your actual driving skills, there's no way to tweak that at one event
