Most of the good points have been brought up already.
I'd say get camber plates, M3 front sway bar, better tyres, a good alignment and see how you go.
From there I'd get M3 front control arms and rear subframe bushings
Then coilovers or a spring and shock kit.
I'm not that impressed with the stock brakes and will be upgrading to Stoptechs.
But I'd say better pads, fluid and backing plates are a minimum. Ferodo DS2500s are better on the track and good on the street (rear pads clunk and squeal a bit, fronts are silent).
Right now I've got all of the above and the car is a better daily driver than when I started and decent enough on the track. It's never going to be the best track car but it's fun.