Carry binoculars and scan ahead periodically. Fleeing wildlife may be an indication of bears in the area. If you see a bear cub, you can expect the mother to be close by. For this reason it is wise to plan you itinerary carefully so that you will not travel at night. Large parties are safer than solo hikers.
Groups tend to make more noise and appear more formidable to a bear.
Also, if there is an attack, there are enough members in the group to render assistance to the injured while others go for help. However, having a larger group is no reason not to pay attention to your surroundings. As a general rule, the noisier the safer. Whistling is not recommended as if may inadvertently imitate another animal, drawing the bear to you. Yell every few minutes to alert bears, especially when traveling upwind, near streams or in thick brush.