How to manage out of stock products?

Context: Apparel E-commerce

On my category page, should I advise my visitors that the product is out of stock on a roll-over product description or should I indicate it once my visitors arrive in the product page (then displaying similar products)?

Should I put these products at the end of my product list ? Completely remove it ? Let it where it is currently place?

Any rules or advices?

Thanks,