probably the best thing you can do is to keep it clean. like spotlessly clean.even a bone stock car looks sharp if its clean and shiney. take bug and tar remover and get all the bugs off the hood and front bumper. take wax and grease remover ( not paint thinner it will soften or remove paint) and get all the road tar off the lower half of the car, especially the rocker panels ( the part of the body that is underneath the doors and lower edge of the front fenders) wax it good, buff the car if the paint shows any signs of swirl or scratches, and wax it. wire any plastic part down with protectant prior to waxing, the wax wont stick to the plastic and turn white.
headlights dull? buff em or replace em with clears.
i agree with statements above about the car looking boxy and not really body kit worthy. too much time and money for somthing that wont look right on the car.
id reccoment a factory rear spoiler if it doesnt already have one, they almost always look nice, and you can probably even find one the same color as the car in the junkyard. if it has a luggage rack on the trunk, take it off. may even consider swapping trunk lids for one that has a spoiler and no luggage rack if yours has a luggage rack and no spoiler- lot less work
replace the front facia with one that is from a higher model, like with factory fog lights etc if yours doesnt have them. maybe even a jdm front end if you can find one.
whatever you decide to do, do it properly, nothing looks worse than a hack job on what would otherwise be a decent looking car. small appearance mods look really nice when done properly compared to some flashy looking stuff that was just hacked onto the car. shoddy work looks shitty no matter what.