If you want to save money don't go to first tier cities (namely Shanghai, Beijing, Guangzhou and Shenzhen) as everything there is om average 30% more expensive than in second tier cities, and rents are between 50% and 300% more expensive than that of second tier cities. Teaching jobs in first tier cities pay barely more than that of second tier cities, you might get 15000 in a second tier and 16000 in a first tier.

If your goal is to stay in an expat bubble or party every nights then yeah go to first tier cities.