Go somewhere busy, preferably a place with lots of people. Imagine that your vision of the scene is a video camera, recording everything. Take out your notebook and write down exactly what is happening. Include all the senses—sight, smell, hearing, taste, and touch.
Take a voice recorder, and spy on a conversation. Don’t let the speakers know! Eavesdrop their conversation. After you've recorded for an adequate amount of time, transcribe the conversation on paper. Play with the words—delete things, change things, add things. Create a new setting or a new situation.
Create a character. What do they want? Fear? What is their secret? Who are they related to, and where do they live? What’s their last name…if they even have one?
As early as you can, set writing goals and try your best to stick to them.