Promissory Contract and Final Deed
The normal procedure is that the lawyer in cooperation with the seller's lawyer work out a promissory contract of purchase & sale.
It lists the details of the seller, the buyer, the property, the sales conditions and any other special agreements.
You will normally have to pay the seller a deposit of 10% of the purchase price at this stage. The contract must be notarized to be legally binding. If the buyer defaults he forfeits the deposit. If the seller defaults he has to pay the buyer double the deposit.
Proper title to the property comes with the final deed of conveyance (escritura) which is signed in the office of a public notary.
All the relevant documents have to be checked before the final contract is read aloud and, unless the buyer understands Portuguese, interpreted in English.
The full purchase price is either paid before or during the signing ceremony at the notary.