How can i get cheaper car insurance?

I have been trying to get a quote for car insurance as i have recently ped, im 17 and i live in London i need to take out a policy in my own name, i did a quote for a Renault Clio 2002 1.2 letre and the result was �5000-7000/year with most insurance companys how can i get this down to below �2.500 ??