Once the archives that keeps notary records for our place is established, we would have to ascertain whether there existed a notary in that place and a in the period we want to research. In case no notary was recorded for that period and that place, and if notary records are the last resort, we could try a nearby place - notaries were often "itinerant" officers, that is, they stopped for some days in a place where no notary existed on a regular basis to make acts. Or our ancestor may have traveled to a nearby place to make a will, or, in case he was ill in bed, the family may have asked a notary to come to their home (the notary, like the priest and the doctor, was a common guest at deathbeds). The notary function in this case was of great importance in avoiding discussions among heirs.
If the research of our ancestor stopped, say, at his approximate birth in 1690, what would be advisable to research in the notary deeds? If he was a person of some standing, he may have gone to a notary to give dowries to his daughters, so from when he was about 40 onwards we could begin to find some of these acts. Then, if we have an approximate date for his marriage and know the name of the wife, we could go looking for a dowry assignment from his father in law (the document could probably contain our ancestor's father's name). Finally, if we have a date for his death, he could have made a will (actually some men made more wills in the course of their life) giving many details on his family.
Once we have a notary for the period and place we need, we have to request the actual books and start to study them. A book may contain more years, but most typically at the end of each year there is usually an index listing type of act and one or both parties in the deed. In case the index is missing, the book is to be examined page after page, identifying the beginning of each deed and the names of the parties. Most notary deed were written in Latin, but Italian was used when the notary reported actual statements of the parties. With some practice, the researcher will easily identify the long legal formulas and jump to the content of the deed.
Notary deeds will allow to identify people and relations among them, but will not give dates of birth or death, which would have to be approximated and derived from vital statistics.