Before you go abroad you have to get your visa. To be able to get your visa you have to get in contact with the embassy or a consulate of the country you are going to. This will allow you to get your visa and learn everything about entry requirements to a particular country (vaccinations, customs rules, visa, etc.). Unless you do this, you are not guaranteed that you will be allowed to enter the country. Some of the countries have a visa-free regime with the U.S. but a lot have certain requirements that you have to fulfill, especially if you are planning to participate in an international internship or a study abroad program! It is your responsibility to get the right type of visa to be able to participate in your program abroad.
A lot of times you will have to visit embassies or consulates to get your visa approved. If you wait too long, you might not have enough time to visit them because most likely it is not a walk-in service. You have to set up appointments and plan them ahead of time. You don’t want to end up being in a situation when you don’t have your visa and your flight is tomorrow. You will have to either reschedule your flight or cancel you program abroad along with the flight. This will be very costly, as you will not get your program fee back and definitely will lose out on your airfare purchased.
You should visit www.travel.state.gov to find more information about embassies.