Overall my internship experience has been great, and there is little that I wish went differently. There may be a few things I wish I knew at the beginning of the internship, but I think these are mostly things that are an integral part of trying something new, and learning them along the way is the only way. These include getting a sense of where everything is, how to get around, using the public transport system, where to get a quick bite to eat or a coffee, and what to do on the weekend. These are all things I figured out on the way, and believe this is really the only way, and was part of the fun of having an internship somewhere new.
One practical thing I do wish I knew more about prior to my internship is information about housing. Not only had I never been to Boston before, and knew nothing of the location, I had also never even moved outside of Michigan before for longer than a week. And hence, one of the biggest struggles was finding a place to live for the summer. I had no idea how close I should be to my work, no idea what areas were good to live in, which areas were more dangerous, whether I should be able to walk to work, or if public transport was the thing to do. I also had no idea how much housing should cost, nor any idea of where to look for housing. In the end I was of course able to figure it out, but it could certainly have gone smoother.
For others who have never moved somewhere new for an internship or something similar before, I would encourage you to do a few things. One, see what you can find out about the area online. Using Google maps and some Google searches about the different districts/neighborhoods of a city is a surprisingly decent way to gather a general sense of the area. Also, definitely reach out to the company your interning at for information about housing. They should give you all the info you need, however, if they are somewhat new to having interns, you might need to reach out to other sources for help. I recommend trying to reach out to the other interns that you will working with, to see how they went about finding housing and if they have any advice. If you happen to know any friends or family from the area, it might be a good idea to hear what they have to say about where to look. Facebook groups are also a good place to post for questions as well as to find pages where people post rooms available for subleasing. If you happen to be interning in a college town, frat houses often sublease for the summer for reasonable prices. Finally, the earlier you start looking for a place, or at least start gathering information, the better!