If your aim is to study in NZ and utilize your knowledge in your home country
Then perhaps the best option is to research the career options that an overseas education may bring to you.
If you want to stay on in NZ and gain permanent residency
I suggest you utilise the following
Rule 1
"Permanent residency in NZ is highly tilted towards skilled employment"
Rule 2
"Do a course that makes you attractive for an NZ employer who may give you a job which meets the criteria for skilled employment"
Now that you know this, I suggest the following steps
Step 1
Research those jobs / professions which are in the "skilled employment" category and find the jobs, professions which you find interesting and could pursue.
Tools to use
Step 2
Research the job market in NZ, job advertisements are the best first hand source of information that you can use
Tools to use
Step 3
Research the courses available in NZ for international students keeping in mind the above i.e. which course will lead you to a profession or a job that you want
Tools to use
English language requirements
You will be required to meet the minimum English language requirements depending upon the course you choose, unless you are going for a "Pathway" visa in which an English language course is included with the main qualification and allows those students who don't quite meet the requirements.
As always your comments and feedback are highly appreciated. Note that this information is current at the time of writing this blog. It is not meant to replace immigration advise, and should not be taken as such.