The best way to become an expert on your topic is to begin finding and thinking critically about information related to it.
Start by seeking background information, such as encyclopedia or overview articles, to get a sense of the history of your topic and major themes or issues. What research has already been done on this topic? Who are the stakeholders involved?
Next, look for news or magazine articles that relate to your topic -- these are written for a popular audience, so they are useful in developing the subject knowledge you need before tackling more advanced sources.
Track major ideas, themes, issues, and questions as you read.