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First of all, it is perfectly fine to drive in the US (including rented cars) on your national driver’s license, you don’t have to get an American one. But there are good reasons to consider getting it. Also, new ID requirements introduced in March 2018 by President Trump administration require all new or renewed licenses to be valid only for the period of your lawful stay, and put additional ID requirements for applying.
Driving license/Liquor ID
You need to have one of these, unless you want to carry your passport any time you want to get a drink or buy beer/wine/choose your poison (no, your national ID card, home country driving license, Harvard ID, library card, etc. do not count, at least in some places). Getting a Liquor ID is easy, but it is worthwhile to get a driving license, since the tests are practically a joke, and it will make your life easier in some cases (air travel, lowering your insurance in the future if you stay in the US or come back in some years, etc.). You start by getting a Learner’s Permit, you learn from the driving manual, and you go from there.
Both Liquor ID and a driving license can be obtained at a local DMV. Better choose the one in Boston, rather than in Watertown (they are much more used to foreigners and make less fuss). Make sure to get your Social Security Number Denial Notice (or SSN) first (10 Causeway Street), and bring your passport as well as another valid picture ID (such as your driving license). Just for casual driving or renting a car on normal basis you can easily just use your home national driving license. Please note: it is not really worth to go through the hustle of converting your national driving license, since you would have to pass the theoretical exam anyway, and also surrender your current license (so the only difference in practice is passing a road test, which you should be able to do unless you can’t drive, in which case you probably shouldn’t anyway).