On a newer car the decent mods would be to keep brakes in good condition or even improve them and of course buy good tires, because too cheap of a tire can sometimes lengthen the stopping distance tremendously.
The other things are driver related, just like some_other_dave sai. I would add:
1. Have a good driving position -> believe it or not, braking distance increases a lot if your seat is too reclined (like those "I want to look cool" kids drive) and if your feet are too far from the pedals.
2. Ease your mind before you get behind the wheel so that you can keep a relaxed but focused mindset. A lot of accidents are due to drunks or just careless people in a hurry. Make a conscious decision to let go of stress and not only will you drive better and enjoy it, life itself will seem much nicer
