the hospital I worked at didn't require anything aside from a high school education. however, I had no prior experience so I figured I'd get certified (through the red cross, I think it was like $800 or something ridiculous- 4 classes 4 hours each)
generally they wouldn't hire someone like me without experience, but my parents both worked at the hospital so I had some pull. I was lucky in this sense. I only worked in the hospital, but you can also work at long term care centers, probably old folks homes too.
the work was sorta miserable. everything from bringing people juice, to cleaning up vomit/shit, bathing all types of people, helping to restrain psychotic patients, doing cpr, and watching many people pass from this life. I can't imagine how people have it as their career, they're stronger people than I am, no doubt in my mind. I had to deal with a lot of really arrogant, moronic, and completely retarded people. but there were some brighter moments