You might already be writing your thesis by publication, with several articles published or in the publishing process. Or you might have completed your thesis and wonder how you can raise your profile by getting publishing some of that hard won effort further recognised by putting some of it in a journal. This information will have some benefit for both situations.
There is one point to emphasise first. Do not expect to cover the information in your thesis when you write a journal article. You can probably cut up the content into various articles. What were your most interesting findings? Have you introduced a new methodology or adapted an existing one? How many separate studies did you make? What research questions and sub-questions did you answer? Which of these would you like to write an article about?
Where do you begin?
Elsevier has a lot of advice. Highlight the key points you want the readers to understand and keep in mind that the point is NOT to condense all your research for your thesis, but to generate a few different articles from it.
The five ideas from the American Psychological Association (APA) on trimming the length can also be very helpful to keep you focussed. On the same webpage, there is also a rather tactful piece of advice on being cautious about how you interpret your data.
Is there a step by step process?
As a quick summary, here are some main points:
Choose one research question or sub-question
Limit your abstract to around 250 words or whatever the journal asks for
Cut your literature review dramatically to what is directly relevant to your chosen research question or sub-question. End it with a clear outline of your hypothesis, aim or research question or sub-question.
Include any relevant literature reviews or meta-analyses in your references to reduce the reference list.
More tips on what to include in your methodology section, your results section and the discussion are at the end of this advice provided by APA.
Step away, then come back refreshed
If you need some help in stepping back from your huge research effort to isolate what you should put in and leave out of a research article after reading over your thesis again, it is probably time to do something else and let the ideas settle. Often some time switching off can definitely bring the best ideas to the front of your mind.