Anyone who hikes on a regular basis can tell you that there are certain things that you absolutely must take with you as you go out into the wild. The first and most important thing is a compass. A compass will help you keep track of where you are and how to get back to civilization when you need to and it can come in very handy if you loose your way in an area that you are not familiar with.
The next thing you must take with you is some water and food. The food should not be something that will spoil easily just in case you are stranded for a day or two. You can take fruit or crackers but do not take meat or dairy products and expect them to do you any good if you get stranded. The water is essential so be sure that you pack enough to last you.
A whistle is something else that is very handy to have in the woods with you. If you wander off in an area that you are not familiar with and loose your way, simply blowing the whistle can alert someone that is close by that you need some helping finding your way back out to a path. It may be the loudest way to call for help as well if you get hurt and are weak from the injury.
Carrying a cheap lanyards with you on your hiking trip can help you keep the essential items close to you at all times. A pouch hung at the end of a lanyard can hold your whistle and your compass and you are sure to have them handy if you find that you need them. The pouch at the end of the lanyard is also a great place to keep your identification.