Read up on the area in which you'll be hiking. Know what kind of animals you might come across and then read up on their behaviour and first and foremost learn how to avoid them. If you're going hiking now, most animals should be fairly complacent as mating season is over and most young ones have grown up a bit.
If you're going hiking alone, make sure your family and friends know where you'll be, what route you're planning on taking and when to expect you home. This ensures that if something does happen to you, help will be on the way faster and they'll have a good idea where to look for you.