You would be well advised to take an external university course in communication. Burwalls, at Bristol Uni used to do a very good course.
Specialist information is not necessary, but desirable, when writing an article. However it depends very much on what aspect of the subject you are commenting. There is also the question of the level at which you are writing.
A low level popular commentary, such as you find in the popular dailies, does not require any depth of knowledge. However, an article, aimed at exponents of a discipline, would.
There is a formula, which you can use, to arrive at an indication of the depth of your article, called the Fog Index. There is a related, but shorter calculation, which will provide a less accurate indication, called Fog Factor. Attention to either will ensure that the level of language, which you use is right for your target audience:
These fog indices and classifications, indicate the relationship between article depth and audience.
0-8 .......... Children's information
9-12 ........ Popular press, superficial information.
13-15 ...... low level technicians
15-18 ....... Higher level technicians
18+ .......... Graduates and higher
Most press articles run at 8-10. Specialist Mags seldom write at over 13.