Bleaching is only one step in stain removal, it’s definitely not to be used to treat regular stains. I use bleach very sparingly, as it will dull and yellow white cotton if used to much. You have to treat the stain and completely remove it.
This site is a godsend for laundry, and I use a lot of her tricks: One Good Thing
Sorry if this is totally obvious, but you have to check that the stain is removed before something goes in the dryer. Once stain is “baked in”, it’s a lot of trouble to remove it, and likely it’s really set in.
I had a guest yesterday that was trying to cover some stained bedsheets so she took off the mattress pad, the sheets and shoved them in the washer. She was just taking the lid off the bleach bottle and about to pour when I happened to show up. I almost had a heart attack and asked if I could help. She was ashamed and was trying to wash out the things. I told her that we’d get it figured out, and showed her how to pre-treat the stain, get it out first, then launder. She said that nobody had ever showed her how to do laundry, and she had a bunch of stained bed sheets at home. Gross.
There are really good resources online, and besides my girl Jillee from One Good Thing, Martha Stewart has really good laundry stain charts and tricks.