Quite a few of my friends have done the TEFL/TESOL courses. They all have to do an actual practical teaching component to get their qualification.

Make sure you do some background research to see if the certificate you receive afterwards is actually accredited. Certain courses online are something more like "in-house training", and the "school" is actually an agency. I found one site which offered a cheap online course, but then demanded a "placement fee" after you receive your certificate - which cost as much as the course! The reality was that their certificate wasn't recognised as valid by itself. As well as doing your research, if you do an online course, there's naturally a lack of face-to-face classroom experience, so you should organise your own practical experience, through tutoring.