In Book 22 of Homer's Odyssey, Odysseus' beggarly rags have miraculously vanished and the hero is revealed in all his glory. Armed with his wondrous bow and arrows, he, his son, and a few trusted servants begin to battle Penelope's suitors downstairs, while Penelope sleeps through it all upstairs.
Before the battle begins, however, Odysseus, in Book 21, tells his servant Philoetius to "to fasten with a bar the gate of the court, and swiftly to cast a cord upon it" (A.T. Murray translation). I'm not sure if this counts as two precautions or not.
Just before Odysseus' command to Philoetius, he tells Agelaus to have the women close off the doors to their part of the house, although it's not clear whether this was simply for the women's own protection or to prevent the suitors from having some other means of escape from the house.
Finally, we should note that in Odyssey 22, Odysseus himself takes up a position near the main door of the hall in order to prevent any of the suitors from from escaping.