Braided Daffodil Leaves
Some people braid the leaves of daffodils.(See picture to the right). The Daffodil Society suggest that daffodil leaves should not be braided because they need sunshine to fully restore the bulb below. If the bulb doesn't fully restore, it can affect blossoms for the following year.
For all other bulbs its best to wait until the leaves are brown and ready to cut. To test to see if the bulb is ready to be cut, gently pull any dead leaves. If the leaves pull off without any resistance then the bulb has taken all the nutrients it needs for the next season and its ready to cut back. This technique is used for all bulbs.