Simply put, if you've signed up for a hilly race, your best bet is to train on hills. Of course the same theory applies to other any other race...training for a marathon, do long runs, training for a trail run, run on trails, training for a 10K, do some tempo runs.
Living in the Conejo Valley provides a distinct training advantage as we have pretty much all kinds of terrain to run on, though in most cases you'll run into some hills. But training for a hilly trail race is easy in the Conejo Valley because we are surrounded by 15,000 acres of open space and over 150 miles of trails. Check out the Conejo Open Space Foundation website for details.
The Edison Road fire road up Conejo Mountain in Newbury Park is a great example of an extremely easy to get to hill that provides some good training for hilly races. Got me breathing pretty hard the other week as you'll hear in this video. Do this 2 or 3 times and your heart may start popping out of your chest :>