Summarize:

You must bring certain documents to your interview so that the asylum officer can confirm your identity.  Bring a form of identification such as a passport. Bring a copy of your Form I-589 and originals of documents you submitted with your Form I-589 (marriage certificates, birth certificates, etc.) If you included a spouse and/or child under the age of 21 in your application, you should bring them to the interview. Your lawyer should have an idea of what questions you will be asked and how you should answer. Try to meet with your lawyer, even if only briefly, to talk about the interview. Generally you can expect to be asked the following:   Provide specific examples of persecution you either experienced or were aware of. Explain the difficulties you anticipate if you return to your home country. Describe the route taken to arrive in the United States. Explain how you got the money to travel to the United States. List any criminal charges pending against you or any persecution of others you committed in the United States or elsewhere. Provide information that proves you belong to a persecuted group. For example, if you claim to belong to a religious group, you may have to answer questions about the religion to show that you are a follower. Your interview will typically be held within 45 days of your affirmative asylum application, although you may have to wait longer if USCIS is experiencing a deluge of applications.  Your attorney may also attend. The interview should last about an hour.  If you need a translator, you will need to hire one at your own expense. USCIS has translators on site, but they are used only to confirm that your own translator is translating accurately. If you apply for affirmative asylum, USCIS has 180 days to make a decision on your application. Because the department is sometimes overwhelmed with applications, you might have to wait longer.  If you applied for defensive asylum, the asylum officer will make a decision relatively quickly. You will be given a written decision.   If the asylum officer finds that you have neither a “credible” nor a “reasonable” fear of persecution, you can appeal that decision to an immigration judge.  If you prevail, you will have a full hearing scheduled to convince the judge to grant you asylum. In other words, those claiming defensive asylum may have two hearings before the judge. However, if the asylum officer believes that you have either a “credible” or a “reasonable” fear, you will have a single hearing.
Collect documents to take to the interview. Practice with your attorney. Attend the interview. Await the decision.