How do make a reservation for a hotel/bnb in Italy? Do you call? Do it online?
Once you identify a place you want to stay, you can email, call, or book online through the hotel of B&B's website as many now have their own reservation system. Emailing or online are easier than calling given the time difference and possible language issues. OR you can use a booking site like www.Booking.com. This is nice for many reasons as they manage the payment system. I like it much better than Airbnb, which for a beginner might not be such a good idea.
Is trip advisor good to use?
As you can see there are many opinions. I do use it for pictures and ideas. I like to read the reviews and see what people really liked or disliked. For example, if it seems a lot of people complain about noise or poor WIFI, I move on.
Do you pay upfront? Hold it with a credit card? If I use my debit
card, do they hold money out? Do you pay in euros when you check out
do use your credit/debit card? How does that work?
Some/Most places require a deposit and especially in high season. Some require you to pay in cash at the time you check in. Others accept credit cards. Some require full payment long before arrival, so you want to be 100% sure of your plans before booking a place with pre-payment. You really have to read all the terms and conditions. I would not use a debit card due to the risk to your bank account in the case of fraud. Use a credit card, only, or cash.