The easiest thing you can do for your clothes: take care of them properly and wash them with gentle detergents!
Instead of throwing your clothes in the dryer, opt to hang dry them instead. This prevents against shrinkage and wear & tear from the dryer.
Fix the minor issues with your clothes! Mend small holes, replace buttons, or even embroider over larger rips.Β
Even as you grow and your body changes you can adapt your clothes to still fit! There is no need for you to stop wearing your favorite pieces :D
When you truly can't wear a piece of clothing anymore, upcycle it or dispose of it properly (whether that be the thrift store or trash).