From Ririan Project, a list of ten first aid mistakes you don't want to do (or have done to you!). For example:
#5. Slapping a Raw Steak on a Black Eye
In the movies, you always see someone put a raw steak over their black eye. While it may feel good, the grease from the steak might get into the eye, causing more inflammation.
“The only medical merit this has is if it’s a cold steak,” says Flip Homansky, M.D., who’s seen his share of shiners in his work for the Nevada State Athletic Commission, which regulates Las Vegas’s boxing bouts. “The cold will decrease swelling, but there is no enzyme or anything else in a raw steak that will help otherwise.” The fact that the steak, compared with blocks of ice or ice cubes, can be formed to fit over the eye is another benefit, but a cheaper and less bacteria-prone solution is a bag of frozen peas, or crushed ice in a plastic bag wrapped in a towel. And remember, you will still end up with bruising.