我做Occupation嘅。
ngo5 zou6 Occupation ge3.
I work as Occupation.

我係(個)Occupation嚟嘅。
ngo5 hai6 (go3) Occupation lai4 ge3.
I am Occupation.

To indicate we are a student in this context, we usually say:
我係(個)學生嚟嘅。
ngo5 hai6 (go3) hok6 saang1 lai4 ge3.
I am a student.
But not:
我做學生嘅。
ngo5 zou6 hok6 saang1 ge3.
I work as a student.

我做Industry嘅。
ngo5 zou6 Industry ge3.
I work in Industry.

我做Type of organization嘅。
ngo5 zou6 Type of organization ge3.
I work at Type of organization.

我返Type of organization嘅。
ngo5 faan1 Type of organization ge3.
I go to Type of organization.

我Duty of job嘅。
ngo5 Duty of job ge3.
I Duty of job.