That's good advice. Make sure you find out as much as you can about a school before signing a contract. Check the blacklists. Be aware that not all bad schools have been repoted, and likewise, some good schools may now have changed directors.

Check out

http://www.geocities.com/hagwonblacklist/

for a list of bad schools. Also, if you have had a bad experience at a hagwon, you can submit it here.