I may have missed it from an earlier response, but what is your HK visa status (if any)?
What field of interiors have you been employed in? Commercial, retail, hotel/resort, residential?
I work at Aedas and we have three big teams - commercial/retail, hotel/residential & resort/casino.
Aedas, Atkins, Benoy, etc are often on the lookout for talented people. The larger companies will often help with visa applications through their HR dept if you are experienced & in demand.
Have a look at the company websites. Aedas lists their current job opportunities and you can send an email to HR - if you are good, then the company may create the opening for you.
Cantonese & Putonghua - helpful but not 100% necessary (depends on the companies client base)
Accreditation - helpful but not 100% necessary if you have the right experience.