What advice can you give to two students who are visiting Estonia for the first time? The first few days we will be in Tallinn and I'm wondering what I can see in this city.

I advise you to plan your itinerary in advance, because there are so many amazing places in Tallinn and you can visit more if you plan your time correctly. If you are planning to drive around Tallinn, then it would be best to find one of the car rental Tallinn, for example, I found this site https://skyrent.ee/ , and find good car in order to make it more convenient for you to move around the city and possibly do more, since you will not need wasting time on waiting for the bus tou need and it's cheaper than a taxi.