Pinching or cutting off the tips of the leaves will cause the cut ends to turn brown. Carefully remove the brown residue after the plant heals itself completely.
Under-watering an aloe plant will cause it to dry out. The tips generally dry out first, causing them to wilt and turn brown.
Aloe plants require full sun and constant temperatures above 41 degrees Fahrenheit. The tips of the spikes will begin to turn brown over time if they are not getting enough light. Keep indoor plants near a sunny window, and rotate the containers on a weekly basis.
Mealybugs and other pests contribute to the overall health of an aloe plant. Keep the pests away by spraying them with insecticidal soap.