Depends if the stain is old or new. I just put the clothes out in the sun but make sure they're wet. If the stain persists use some lemon juice. (Works great on poop stains too)

I live by Simple Green! My mother used it before me and her mother before her. It's gentle enough for baby items and harsh enough to get any stain out. It can be purchased at most stores and won't break the bank like a lot of stain removers.

I like Shout stain remover. It works wonders especially when she has a blow out.

It's called awesome you get it at the dollar store and I swear it's better than every most expensive thing you can buy. Safe for baby clothes and I use it to get grease out of his daddy's clothes