1. Check the Tags.
2. Dilute the Bleach.
Never pour bleach directly onto fabric. If you don't have a bleach dispenser on your washing machine, allow water to feel up partially in the washer tub before adding bleach and then clothing.
This will protect your clothing from damage.
3. Don't Mix Bleach.
Never mix bleach with ammonia or any product containing ammonia. The fumes are toxic and can make you very sick in a very short period of time. If you're in doubt, don't mix.
4. Know your Fabric.
Some fabrics should not be bleached including flame retardant clothing, silk, acetate, spandex, rubber, and elastic. Even bleach safe fabric can be weakened over time with extensive bleach use.