Montressor spells out some of these details in the very first paragraph of Poe's "The Cask of Amontillado."
At length I would be avenged; this was a point definitely, settled—but the very definitiveness with which it was resolved precluded the idea of risk. I must not only punish but punish with impunity. A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.
Above all, according to Montressor, vengeance can be successful only if the risk of being caught is remote. Therefore, Montressor planned his murder of Fortunato with careful attention to detail. He made sure that his servants were gone on the night of the crime; there would be no possible witnesses. He made sure that Fortunato was drunk beforehand. He lured Fortunato with a temptation that he knew his "friend" could not resist--a rare bottle of Amontillado. He made sure that Fortunato had no doubts about Montressor's apparent sincerity. He came with the proper tools for his job: a trowel and mortar. He made certain that Fortunato's screams could not be heard. Fortunato's final resting place was one that could not be easily found.