Hello,
You should be very careful with what you're spending so as not to exceed your budget. I almost failed to do that one :/ It is hard, I know. A good tip is to save money by having your largest meal at midday or by having a good breakfast and then dinner around 20:00. It is best if you eat only one restaurant meal per day. You good take some snacks from the local supermarkets to chew during the day.
I was happy that my favourite coffee cost around €1-2 (take away order). The famous scoop of gelato costs around €1-2. I found one of Naples’ world-famous pizzas at €5! Pasta dishes can cost around €7-15 while meat could reach prices like €25. If you take side dishes like veggies or salad you might pay around €5-10.
For some of Italy’s top attractions you'll need to calculate the following: Colosseum €12, Vatican Museums €16, Uffizi Gallery €14, The Last Supper €8, Climb the Leaning Tower of Pisa €18, Pompeii €11, 3-day Roma Pass €36
These were the prices when I went there. I suggest that you plan a daily budget and make your program accordingly by dividing the amount you'll spend for sight-seeing, food and transportation. It is better to get a pass (wherever it is available) that will allow you to see more, by paying less.
Remember to save some money to get presents for your loved ones at the end of your trip...