Creative writers are naturally attracted to the writing process, but don’t always know what to write about. Experts have something to write about, but aren’t always prepared for the writing process.
As an expert in your subject, it makes sense to share your knowledge with others. This helps you to enter into a dialogue on the subject with other experts and allow readers to benefit from your knowledge. The additional publication credits will help others to learn about you and you might gain additional opportunities from the exposure.
Here are some suggestions on starting to write and submitting your work for publication:
Set aside regular time to write. Blocking off the time on your calendar (even setting an alarm!) will help you to not only find the time, but use it well. (More on writing discipline here.)
Give yourself assignments. You might respond to current events, respond to recent articles or blog posts or review books. Think about questions that friends and colleagues ask you about your work. You might respond to them in an article meant for a larger audience (if they have a question, probably someone else does, too.) Attend lectures and conferences and write in response to what you learned there. This will help you to meet more people, too (you've heard it before: "network or not work.")
Create deadlines. Give yourself assignments and deadlines. This will help to keep you motivated to finish. You might find friends (in the field or strong editors/copyeditors) and ask if you can send them work regularly (according to your pre-set deadlines.)
Submit your work. Find at least three venues (that you would be proud to have your work in) and examine the submission requirements. Write to fulfill their requirements and submit your work.