my basic approach is quality and timely maintenance and when things break/wear out install better. i modded to preserve my 100k warranty then phase 2 after.
Regular maintenance like wax exterior, clean interior, regular oil change, water wetter are not expensive. when things get replaced install better example irridium sparkplugs total $24.
so what else to upgrade? set goals for the car that fit your lifestyle and budget and read nasioc and read again.