When you find a property in Italy, you will probably be asked to sign a Preliminary Purchase Contract (Compromesso di vendita) and pay a deposit. If you don't speak Italian, make sure that this Compromesso is also translated for you and that the clause "subject to mortgage finance" is in the agreement. This will cover you if something goes wrong with obtaining mortgage finance. We would always suggest that this contract is drawn up, but that you do not sign it until you have mortgage approval from a lender and after a survey of the property has been completed. This contract will usually state the agreed purchase price and completion date.
Alternatively, you could agree with the seller to sign a Purchase Proposal. This is not legally binding and simply states your intention to buy, and the sellers agreement to sell, the property at an agreed price and date.