The List could be endless,,, Depending on what you want...
Power
Handling
Brakes
Cosmetic looks
Oem+
Aftermarket
My 1st mod was a Cold air intake, then brakes, handling mods.
Then to back things up for more power
Dv, Exhaust, a good service etc....
After that some cosmetic mods
Everyone to there own, it's just the way i did it
Your best value for money would be IMO a CAI, re-map, engine mounts, exhaust, WALK.