What can i do to avoid kidneys stones?

Plenty of fluids...: Calcium oxalate stone=common type and excess of these two substances (calcium + oxalate) in presence of concentrated/acidic urine allows formation of stone. Dietary intake of the above may contribute to stone, but the effect is mainly acidity in urine--thus minimize acidic juice/foods and consuming plenty of fluid at all time, even in middle of the night, will reduce risk. Consult doc. Good luck.

Drink water: There are a variety of conditions that predispose to kidney stone formation. Ultimately, one must stay well hydrated to keep urine output to about 2 liters per day. Also avoidance of excessive salt intake is a good measure. Some other conditions require more extensive treatments, medications, and even surgery to prevent further stone formation.