As always, wading through the
efficiency mods and
hypermiling tips is a good start.
See what you're already doing, see what you could easily do, see what you're comfortable with to try it out.
A grille block and increased tyre pressure are about the most widespread modifications.
Coasting down is one of the more popular techniques - wether with the engine off or on.
Seeing it's a lean-burn engine, try to spend as much time as possible in lean-burn mode. Look of the boundaries of the lean-burn, and try to expand the lean-burn envelope with your mods.
On sports hatches, the hatch spoiler is usually dubious.
It might work for you, improving mpg, but it might very well work against you.
You might want to try closing the gap between the spoiler and the roof, and turn it into a roof extension.