20% of the cholesterol comes from food and 80% from the liver production.
You can work on that 20% avoiding foods rich in cholesterol (pork, lamb, organs, eggs, diary products rich in fat), consuming lots of fibers (they are reducing the absorbtion of cholesterol).
What you can eat: vegetables, starch, meat low in fat (chicken, cow), low fat fish, low fat diary products (under 2% fat preferably).
Vegetable oil does not have cholesterol but it is transformed in cholesterol in our liver, so avoid mayonnaise too, avoid fried foods.
The pills will have to deal with the rest of 80%. Statins are the drugs of choice. If you've just been diagnosed and started the treatment, you should be reevaluated after 6 weeks, then at 3 months interval, the dose should be adjusted til you reach the goals.
Other measures: walk daily at least 30 minutes, don't smoke