When I started writing I always looked for tips on hosting write more effectively or how to craft better characters. Since most writers do not necessarily start out in a classroom setting when they first start out, or even those seasoned writers that are always interested in learning a new technique to try out on their next piece.
Step - Write in the Midst
Write for a minimum of 45 minutes about two people arguing. Use a crowded place as the setting, and describe both the surrounding and the interaction between the characters. This technique was a bit of a struggle to achieve. Crowds can be a nuisance to some writers, but it often has worked to challenge the focus of a writer by trying to write in a midst of a large group of people.
If the though of trying to write somewhere where a lot of people gather then I challenge you to start small on this task and pick you local barista (Starbucks, Coffee Bean, or regular coffee shop). You get a good amount of different people to observe while you write. Even before I started watching I realized that I loved to watch people, and how they interacted each other. This step is meant to help grow your ability for character interactions. Believable characters can only work if you can make their interactions with other characters believable. You can repeat this step as often as you like while your writing about a new setting, but for the first few times I would limit the amount of characters to two, and then build from there. If you have too many characters interacting at once it can be hard for both the author and the reader to discern. Though that does not mean that multiple characters talking at once is impossible, several authors use this technique often in larger works.
Give it a try, and when step two appears you'll be ready to take the second leap.