Put on clothing with long sleeves and long pants legs for protection against the stings of any wasps that might still be in the nest.
Place the ladder sturdily against the tree. Make sure the ladder is close enough to the nest that you don't have to reach too far.
Place the plastic bag over the nest and tie it shut over the branch or the stem of the nest.
Cut the stem of the nest with scissors; use a pruning saw to cut through the branch if it is small enough to carry inside. Sometimes people enjoy leaving a bit of the branch connected to the nest; it adds to the decor value of a preserved nest.
Cut the branch down with a pole saw if you don't have a ladder. Take care that the branch will not damage you or any property when it falls.
Place the plastic bag with the nest inside the freezer for a few days or simply leave in the garage for a few cold days. Wherever you lay it down, be sure it is protected from the weather. The thin paper that makes up the nest is destroyed by winds and ice. While wasps and hornets abandon their nest in late fall to die, there may be a few stragglers left behind.
Display your nest in your desired location.