If you plan on going hiking, even if it is somewhere that you are familiar with, you should always take a bug-out bag. A bug-out bag is basically like an emergency kit that you take with you when you go hiking so if you get hurt or get lost, you have emergency supplies to keep you safe.
You want to have tools that will help you get un-lost in your bug-out bag. You should always take a printed map of the area where you will be hiking. You should also bring along a compass to help you navigate and use your map. Additionally, if you have a portable GPS system, pack that as well as a back-up battery. You want to have the tools to find your way back to a safe spot in your bug out bag.
You want to make sure that you have items that will keep your body safe in your bag. That includes items such as sunscreen and sunglasses. In the winter, that would include a thermal safety blanket to keep you warm.
You are also going to want to have medications in your bag as well as a first aid kit that is full of supplies. A first aid kit will help you should you get injured and ensure that you don't get hurt.
When you get lost, you want to make sure that you have the energy to walk to safety or wait for assistance. In order to do that, you need food. You are going to want to have non-perishable food in your bag, such as trail mix, granola bars, dried fruit and jerky. These types of foods will fill you up without taking up too much space in your bug-out bag. If you bring canned food, make sure that you have a can opener.
You also need to make sure that you a fresh supply of water. Bringing a filter to clean any water that you find is also a smart idea as well; that way, you will never run out of water.
You also need survival tools. You are going to want an LED flashlight that will last for a long period of time. You are going to want to have fire starters, matches, and magnesium stick. A knife can be a really handy tool when you are lost. A cell phone and extra battery or a two-way radio will help you communicate. Pack a tarp and a space blanket to keep warm and allow you to set up a shelter.
Your bug-out bag should be able to provide you with food, water and tools to survive for a period of time should you get lost or injured while hiking.