If you are a westerner use echinacities online. A lot of work is 'word of mouth' and through contacts which takes time. You could also try recruiters but they will probably cheat you.

echinacities is an awesome place to find jobs. For teaching jobs, Dave's ESL Cafe is also good.

echinacities is the worst site to find a job
serious this site is good but they need a school/ recruiter review section like daves esl
you hear me cats!!!!!!!!!!!!!!!! get a school/ recruiter review section

Find and investigate a school, always talk with a teacher from that school, not the head teacher but a real worker, they give you the real heads up. Try to stay away from training schools and see if you can find a foreign operated school. If you plan on leaving a private school, let them renew your visa first, after that besure to get your passport, give a thrity day notice and ask for a letter of release and cancel your foreign expert certificate. I only say this because in a contract it says both parties must give 90 days to say if you will stay or go, most schools will not do that and wait until your visa is about to expire, then they will hold you by your visa.

1) go to the human resource exhibition show. Browse the want ads, hand in your resume and interview on the spot.

2) Send application on websites:
www.51job.com
www.jobcn.com
www.job5156.com
www.zhaopin.com

refer to http://www.echinacities.com/expat-corner/5-ways-for-expats-to-find-new-jobs-in-china.html

For teaching jobs, there are so many sources.  Some  have talked about Dave's ESL Cafe.  Dave's ESL Cafe, at least the China Jobs section, usually carries adverts from those schools who for one or the other are not exactly the top choice of places one would wish to work for in China.  Newbies don't know that when looking there and they are inclinded to think that it is a marvelous list.

For Beijing, try the Beijinger (www.beijinger.com).  For all of China, try www.eslteachersboard.com, although the site has really changed over the years (going from direct hire to agency recruitment). Additionally, www.abroadchina.org is a good portal to use for a job but the process there is slow and cumbersome.

The biggest agent in China is Angelina's Cafe in Beijing but service can be less than satisfactory and one needs to pay a lot of attention to the "bait-and-switch" routine (www.anesl.com).

Echinacities does have a growing and very active list and employers that used to advertise on www.eslteachersboard.com seem to have migrated there.