While an idea may come to you anywhere at any time and end up being scribbled on a napkin, blocking out the same time each day and working in the same physical space may help you with the work of turning the idea into an article. To begin, ask yourself what the central idea is and how it affects the readers. It helps to summarize the main point even if you later decide to add something creative before it. Detach from the world and allow the task to consume you. Don't worry about grammar, spelling, and syntax when you begin, and don't allow self-criticism until you get to a stopping point.
Early criticism can stifle the creative flow.
Stopping to look up a fact or figure also can derail your train of thought, so indicate what you want to insert later and move on. If you encounter writer's block, you may need more preparatory work. If you feel you have done all your homework, force yourself to write something anyway. Write in a personal journal. This removes the pressure to produce acceptable material but starts words flowing.