i'd say work from the front to the back. investigate a grillblock perhaps a wiper shield as the hood looks as though it would lead the air right into the wipers... not a disaster, but things can always be smoother.
a front understray and wheeldams are also quite easy and effective, but a small airdam can work too
a kammback would work too and it wouldn't have to be all that big, it could take the form of a custom spoiler with side fairings
like this for example
