Getting Your Airline Tickets and Lodging Arranged
Airline Tickets
There are tons of great websites out there to help you find a great deal on airfare, but your first stop (if you're under 25) should be STA Travel.
One of the best sites around for aggregating multiple websites and comparing prices is SideStep.com. SideStep searches tons of travel sites and airlines, but unlike many similar sites offers customized views and the ability to exclude certain airlines that you're sure you don't want to take. Similarly, FrugalMonkey pulls together information on auctions, tickets, and other deals all in one place, making it easy to weigh all your options and find the best ticket.
Lodging
If you're traveling with a program or school-sponsored trip, you'll probably never need to worry about housing, perhaps having to fill out a few forms and marking preferences. However, if you've secured an internship on your own, you'll need to find a low-cost place to live that's convenient to your workplace. Do some initial research about neighborhoods in the town or city in which you'll be living, and consider housing yourself in an inexpensive youth hostel for a few days while you get your bearings. You may be able to find a home stay (a room with a local family) where you pay a small monthly rent in exchange for a meal or two per day, and sometimes even laundry. To find situations like these, check into whether your city has an active Craigslist, or contact that local university that may have a study abroad program in the same area as your internship and ask them how they house their students. Often, universities have deals with hotels or apartment complexes, and they might be able to pass those discounts onto you even if you aren't traveling with their group. This is especially true if you are an alumnus, which is why it is best to begin with your own school, even if you may not be in the area any longer.