In order to write on a wiki you must first decide what features you want for your wiki, or for writing your first article for a wiki.
Writing a wiki requires research.
Make the information on your wiki clear so visitors can easily view and contribute to it. When working on a wiki there are a few things to consider' as well as guidelines that should be followed. One tip that should always be remembered is to keep it short. Writers should also use active voice, and avoid passive voice except in subjects they aren't familiar with. To better engage your vocabulary in your post, try using strong verbs. Always remember to cite your sources, and give credit to where you got your information. A writer can also link readers to other, more detailed, supporting information with hyper-linking. This type of link sends readers directly to your supporting pages. Make your post interesting by using lists, bold headings, and block quotes. Use common sense when composing your entry. "Thus Wikipedia is not only a reference source, but it is the acknowledged site on the Web for claiming an interpretation of knowledge, as well as a place for controlling public image on an important gure. Both of these functions are substantial and substantially beyond the scope of a traditional encyclopedia".
Know the components of research: Make notes on the things you would like to cover on a wiki.
Keep in mind that research is just that: Re-Search. You must do both, together again and again to impact your scholarship with surrounding sources you find on any subject. Find (at least) three sources that agree with where you are going. Outline the points you would like to make, and step forward with your research. Make sure your resources are from credible sources. These will include books, articles or encyclopedia(s).
When finding the main points you would like to make from your research, create an outline. An outline: is comprised of hierarchical uniform information, from most important to least. An outline produces the points, in a type of order to create organization. 
Creating the Unbiased Voice
An unbiased viewpoint promotes a reliable viewpoint that invites criticism, which is essential in contributing to a wiki. When contributing, make sure before presenting information on a wiki to carefully separate your opinion from the subject. Wiki's are different to academic research papers, blogs and podcasts in the respect that a wiki is never finished. Get straight to the factual points you wish to make, and jot them down.  Make sense of the points as best you can from your resources, and take out any hint of awkward wordiness. What makes Wikipedia credible is that the unbiased voice is crucial. Having an unbiased voice invites others to correct wiki-work and be able to contribute in the same fashion that you have. Maintaining a wiki is a collaborative effort. "Publications on wikis in education range from descriptive efforts to characterize wiki learning activities and cultures, prescriptive efforts to establish guidelines for implementing wiki learning activities, and a few design reports that document technological innovations to support classroom use."
Choose a Wiki
Depending on where on the interwebs you would like to write your wiki, try out looking around at the current list of wikis.
Use the Wiki Markup Language
To not come off as a novice, be sure to use the appropriate format when delivering information. Simply use the correct headlines, bold when necessary, and link to as many sources as possible to nail in your point more effectively. It is always a good idea to have a wiki cheatsheat when necessary. However', it is absolutely necessary to understand how wiki markup differs from HTML or CSS. This will benefit the likelihood of future posts to wiki. Careful: When using appropriate markup, be sure to make your wiki article navigable with enough contents to browse. For example, this site uses MediaWiki.
Double-check what you have written, use a spell checker, and try reading your work back to yourself to see for clarification.
Cite your sources
Learn how to cite your sources online. Contributions are hardly worth reading if credit isn't given where it is due. All information comes from somewhere, inspired or leaked from a beginning source.
Wikipedia and MediaWiki both use the <ref> (reference info here) </ref> tag set for referencing. For instance, this [#] at the end of this sentence references this page. Look at the source code for this page to find the following code:
Reference lists usually appear at the bottom of the wiki page. The wiki will automatically add whatever is inside the <ref> </ref> to the reference list.
MediaWiki Reference List
Ensure there is a References section on the page. If one doesn't exist, use <references /> to include one. Preface it by including a section header for References, Links, Citations, etc. See the source for this page for an example.
Wikipedia Reference List
Ensure there is a References section on the Wikipedia page. If not, create one using this tag:
- Matthew Barton, Robert Cummings. Wiki Writing: Collaborative Learning in the College Classroom. University of Michigan. Jan. 2009. Print.
- Judd, T., Kennedy, G. & Cropper, S. Using wikis for collaborative learning: Assessing collaboration through contribution. Australasian Journal of Educational Technology <http://www.ascilite.org.au/ajet/ajet26/judd.html> Web. 9 Nov. 2013.
- Ward Cunningham, Bo Leuf. The Wiki Way: Quick Collaboration on the Web. Addison-Wesley Professional. April. 2001. Print.
- http://www.andreaforte.net/ForteBruckmanConstructingText.pdf Andrea Forte and Amy Bruckman. Constructing Text. Wiki as a Toolkit for (Collaborative?) Learning. n.d. Web. 9 Nov. 2013.