Consider carefully what level and age of student you would like to teach. You can choose from kindergarten through university age and above. You may not realize how much you like teaching younger students or vice versa. I find that the best rewards usually have come from the students in private language schools. Most are willing and even eager students. Working in public schools was much more difficult in some ways. You may have a class of 60 or more students so that in itself is a huge challenge. Chinese students are ranked and recorded throughout their academic life. Scores from testing determines which students will be sent to the higher ranked schools. The best of the best end up at Beida, Peking University, or Qingwa in Beijing. Most political types would probably choose the later as 7 of 9 of the top government postdating attended Qingwa. So naturally some schools are populated with students who achieve or test higher. Here is another twist. In the West private schools are often thought to have better educational systems. In China, many of these schools are populated with students who could not test high enough to get into a school that was highly rated. They may belong to families that can afford it so they go to a private school. The teachers may be perceived as better or the class size may be smaller. You still may end up with largely disinterested students.
Private language schools can be a great choice or the worst choice. You will have a heavy weekend schedule and days off during the week. The pay will be better than most public schools which usually is 3-5 thousand rmb. The average teacher with a BA should be able to get 5000 rmb per month in most schools. MA's maybe 6000 rmb. There are plenty of message boards to find out about shady operations. One can also find jobs that pay much closer to western wages. If you are good enough and have the experience you could make 2000 dollars per month. These type of positions always require advanced degrees, certificates and usually experience in China. They are usually joint ventures between foreign universities and Chinese universities and may offer diplomas from the foreign university. The other way to make the higher salaries is to be the director of one of the larger schools, like a kindergarten.
University teaching is another choice you have. You will need at least a BA. Teaching hours range from 14-20 per week. This may be based on a 50 minute teaching period. Always check the details. You will have less classroom hours and more working hours away from the class for prep, and marking. Some schools have tons of off hour activities too, so you should like that age group if your going to teach at a university. You may also find a large degree of lethargy in some schools which may not feed your need as a teacher. Challenges at every corner.