Full service, change all fluids. New brake pads (QFM HPX) and new Super DOT4 brake fluid. Change suspension if they're worn. Replace any worn bushes. Buy better tyres, wider wheels if they're standard. Most importantly, learn how to drive.
No point putting a turbo on your N/A car when you can't turn and brake. Unless you want to piss away thousands of dollars to wrap your car around a pole/tree/another car. Wait until you have full license, then sell the car and buy a GT-t as mentioned.