In Hong Kong, the requirements to be an English teacher are MUCH more strict than in the Mainland.

And they will call your University to check your qual. in Hong Kong, your degree must match what you are going to teach.

I will hear about whether I have been selected to be on the primary NET scheme in Hong Kong anyday now. I have applied to a couple of jobs so far without replies so far. 

I recommend to you to start as a regular teacher in China and to expect to gain more experience, so other employers like you in the future. Hope I could help

Dessy

You could probably find a Shenzhen job easily enough if you search online.

Can't speak for HK, your asking two entirely different questions here.

Build your resume up and you can check out some teaching videos and get tips on how to teach. If you have a teaching certificate then that means you've done your training and you should be cut out to be a teacher. Just practice on perfecting your lessons. The more you practice the better you'll be at it. Remember recognition is always important for students if you don't recognize them in some way they won't feel comfortable. Always start your class with roll call so the student has a sense of belonging there. 

Hong Kong? They will be much more demanding of your qualifications than Mainland China.

In order to teach in proper schools in HK, they will require the teachers to have a education degree and certain years of experiences as far as i know. But you could easily get a job in some of those smaller language schools.

Shenzhen would be so easy to get a teaching since no foreigner is willing to live there, the demands are high.