First of all, what we are thinking about your own car? Looks, comforts, driving quality or anything else.
here few tips are : -
If you have a car, you can modify color of your vehicle through paint or wrap( color wrap) . Obviously! color paint is expensive so you can wrap our car with color sheet. which is available at low cost. if your car color is white then you can wrap your car roof and bonet with black color., same you can apply with red color car or any other color cars, as per your wish.
If you want to comfortable drive then first thing comes in your mind while driving the car is comfortable seats. For these issues you may put Art leather seat covers which is low cost seat covers as compare with other leather covers.
How can we forget about Music system. music system or infotainment system plays an important role in you car. so, you can install pioneer or sony music system both are having very good quality with JBL speakers.
When we comes on driving quality? It will be solved by tunning of suspension. In India suspension also having an important role.
Why not Navigation system? . Navigation system helps you to provide accurate direction towards your destination. It contains satellite maps which provides you accurate position via road map or speech.
conclusion : In my view, you can modify your vehicle as per your priority but it should not be risk taking priority through extra modifications on cars. In my suggestion go for minimal enhancement or modification because it always reminds your best memories with your fun loving vehicle.