I have the same exact car and I tinted the windows last week, 30%-front and 5%-back and it already looks a lot better. So to start off, do that first. I'm also thinking of putting a custom sub in it because the original one doesn't work anymore. Later on, I might install a pair of 18s or 19s, I'm not sure which ones yet.
So do something to that effect. I don't know really know how you would like your car to look but these are some ideas that I might use in upgrading my car.
P.S. If I do install the 18 or 19 in. rims, I might lower it just a bit, but that depends on how it would look with the wheels.