Cellulite is often genetic. Even skinny girls can get cellulite - pics of Paris Hilton in a bikini with visible cellulite on her thighs were splashed all over HEAT magazine last summer. And here are pics of Misha Barton's cellulite http://theskinnywebsite.com/site/2006/09/07/mischa-bartons-cellulite/ [theskinnywebsite.com]
You can try dry brushing in a circular motion to increase circulation, which works for some people. Try creams with caffeine to reduce swelling. And if all else fails, endermologie.