Where is the best place to if we looking for wholesale mobilephone case in Shenzhen?

It is best to go to local Huaqiangbei Commercial Zone, where you will have many choices.

Is it easy to shop there or do i need a translator

Yes, it is generally easy to shop there and there are also many foreign people. Take it easy!

As you wanna take a wholesale, you'd better be accompanied at least a Chinese person, so that he or she will help you to bargain!

Where can i find a Chinese person i can trust

If buy phone case, I suggest SEG Telecom Market and Yuanwang Market. And I suggest you to take a Chinese friend to go with you if you have, because most shop owner do not speak English.

I posted some information about Huaqiangbei on my Facebook, maybe they are useful for you.

BTW, I am a Shenzhen citizen with 5 years electronic experience, can speak Mandarin and English, if you need a guider, I can be helpful. I guided a lot of foreigner, for personal or business, especially if you need a person to deal with your business here, I will be able to sourcing, collecting, QC, shipping and so on.

If you need any help, reach me at cnuniquefoxmail dot com.