Polyurethane bushings and good tires will make a world of difference. If it's a rubber bumper car, lower it to chrome bumper height.
Some people will tell you to uprate the sway bar, lower the car more, run stiffer shocks, etc. These can make an improvement but aren't always good for road use. I'd take it one step at a time so you can see the difference each part makes. Since there is no "best setup" for everyone, tailor the car to its driver instead.