Doing extensive research is crucial because every visa category has its own set of rules and requirements. An excellent source of information on a variety of visa catelive slotsgories, including both immigrant & non-immigrant visas, is the US Department of State website. The next step is to fill out the required application forms after deciding on the right visa category. The most popular non-immigrant visa application is the DS-160, which asks for personal data, travel itinerary, & background information.