any tips on losing weight?

I want to lose about 40 lbs. I'm 14 yrs old and I weigh about 185 lbs. I'm extremely self conscious about my body and I need to lose at least 20 lbs for my health physically and mentally. Also, any extra tips on making your boobs smaller? I wear DD's and I get people looking and I dont like it. I'm far too young to have gross old men looking at my boobs.