Clear up water stains

Leaks in roofs or ceilings will cause brown water rings on drywall but before you assemble everything you need to paint over them, try spraying a mix of 10% bleach to water on them. Wait 24 hours and more often than not, those unsightly brown spots will have disappeared. This will clear up most stains on flat or popcorn ceilings, just be sure to protect your eyes and anything close by that could get bleach on it.