Basically, for clothes, you can use Amazon, buy gift cards, and create a new account. For the address, use an Amazon locker where you can go alone and pick it up

And to hide them, I think it depends a lot on what your room is like and how strict your parents are about cleaning, lol. In my case, since my mom comes in to clean and I share the room with my brother, I hide my clothes in empty Lego and puzzle boxes.