start with the basics first. i just purchased an innova(e) manual dsl last december 29, 2011.
and to my surprise, basic accessories such as mudguards and engine undercovers aren't included yet.
i did it in the following order:
mudguards - is a must. reasons? the name itself will tell you
door step sills - need to protect your door steps, specially if someone with high hard heels usually get in your car
spoiler with led light - a 3rd brake light would be helpful
sun visors / rain gutters - if you feel like driving with open windows, this should help you a lot.
once you get all of these, you can go on with other accessories.
just my own opinion