The sun is lovely and we all think of it as a friend and a giver of life, but take notice that it can be also harmful! If you don't want to burn yourself very badly, use sunblock. Of course a tan is adorable, and don't worry about tanning yourself, but at least put sunblock on your back and nose. They are the first to burn.
This is probably a commonly known fact in most countries, but since I come from Finland, where tapwater is drinkable, I just want to put this tip here anyway.
So, don't drink tap water, it is not clean. People buy water from all grocery stores and all "tabaccherias", tobacco shops (see General Tips). Water is quite cheap anyway. :D