Fronting. Technically illegal but loads of people do it, I still do it and I'm 22!
Basically someone else (an experienced driver, usually your parents) takes out the policy in their name and you are named as an occasional driver.
If you don't want to go down the illegal route then getting one of your parents to be a named driver on your policy usually brings the price down a bit.
What car are you looking at? Engine size is the not the be all and end all. Diesels are usually cheaper to insure than petrols. A lightweight car with a small engine may be more expensive to insure than a heavy car with a slighltly larger engine.
Also the typical boy racer cars will be expensive to insure no matter what engine size. It might not be cool, but a more boring car will save you money on insurance.
You may also wish to go down the extreme route, certain insurers will give young people a cheap policy provided they don't speed and/or drive at certain times of day or night, usally friday and saturday nights to prevent drink driving.
You prove this to the insurer by allowing them to fit a GPS tracking device to your car, which allows them to monitor your average speeds, and will let them know if you drive at a time you aren't alllowed to. It also doubles as a tracking device if the car gets stolen, which is reassurance for the insurer.