School just let out and i really wanna lose wait any tips or tricks?

im 12 years i weigh 151 and im like 5'0 exact. i suck in my tummy all the time so my friends will think im skinny but im tired of that i want to be able to were a two piece and feel good my thighs are also problem to the supper big we jut got out of school in june and go back i september so any weight i could lose from now and the i have a gym and i canot run because their are way to may petifiles where i live thanks oh and btw i am in cheerleadig dacing class tumbling and next year ill be in track ad volleyball along with the others