Writing is made easier when you know the reasons you are writing. Journalists do this by answering the so-called "5 Ws and 1 H": who, what, where, when, why and how. You can do this, too, by deciding who your audience will be and what it is you are trying to explain to them. Determine if you are persuading your audience into action or if you are telling a story. Figure out where and when your writing takes place and why it has happened. The last question you ask yourself is how the audience is to take action.
In order to generate free thinking about your topic, use a blank page and write on the topic for five minutes. Write down everything that comes to mind and do not worry about grammar or spelling. Do not eliminate or criticize any idea -- no matter how outlandish it may seem. Do not worry if your sentences make sense to anyone; be open to everything that comes to mind. The use of brainstorming as a pre-writing tool helps writers explore the topic completely and unleash any form of writer's block.
Use a blank piece of paper or dry-erase board and have an eraser handy. Write down the most important word or phrase in the middle of the page and circle it. Place other important words outside the first word and draw connecting lines to the first word. Also, write words that detail the second level of words and connect them to the second level. When you run out of words, step back and look at all of the words or phrases you wrote. Think about how each one relates to the original word. Move words around and erase words that do not fit into the writing or your message.
Now that you have a general idea of your topic and what you would like to include in your writing, the next step is to organize those thoughts and ideas into a logical order. The thoughts you came up with during the previous steps will become more of a linear story. You do not have to create a formal outline; just jot down the order you want each concept to appear in your writing. This step is beneficial to make sure that no important pieces of your exploratory work got lost in your pre-writing mode.