Tint on the windows? That is a good choice for the first mod.
Interior lighting ... my brother installed pink led's under my driver and passenger footwell. He hooked it up to the 'mirror' fuse. Otherwise if it was a switch, I would forget to turn it off (I did in my previous car and it drained my battery, lol). This way it comes on every time I drive the car and shuts off when the car turns off
