What should you bring?

Water

This is the single most important thing you should bring. How much water is difficult to say. On a hot day on a trail with a lot of elevation gain you may need 1 pint per hour on a cool day you may need much less. You should try to make your best guess on how much you need. Do not substitute water with soda. Drinking soda will not hydrate you like water can.

Food and Snacks

If your hike is going to be more then a couple of hours you should bring a snack. If the hike is all day then you should bring a lunch. Bring any food or snack that you like that will help give you energy. You don't want to to run out of energy and struggle to get back to your car. I would suggest that you eat any food that is a part of your regular diet that does not spoil. Don't take things like a sandwich with mayonnaise on it. The mayonnaise will spoil and could make you sick. For day hikes there is no reason to spend a bunch of money of dehydrated food that you have to cook. You probably will not enjoy them like the will the foods you like and you will waste time trying to boil the water.

Good shoes or boots

You need to have comfortable shoes or boots for hiking. If your shoes or boots are not comfortable or are too tight you will develop blisters. Also don't forget to cut your toe nails before hiking. Long toe nails will rub against your other toes and cause problems. You do not need to spend a lot of money on special hiking boots. I hike in my Nike running shoes which I prefer over hiking boots.

Sunscreen

If it is summer time then you will get a sunburn if you don't have sunscreen on. Remember you are going to be out in the sun for several hours. You may need to reapply sunscreen after a few hours. It is even better to cover up any exposed skin with a hat or clothing. Keep in mind that high elevations expose you to stranger rays from the sun.

Mosquito Repellent

although not always needed you should have for the times when you do need it.

Map and compass

The last thing you want to happen is to get lost. You need to have a map and compass and know how to use them. The map does not have to be a paper map. You can use a map on your phone and a compass app. I like to use google maps offline. Since there is likely no cell phone service where you will be hiking you should not depend on cell phone service being available. Find out how to download a google map offline and download it before you go. If you get lost you can use google maps offline to see where you are at and how to get back to your car. I also make sure I have an external battery pack and power cord for my phone because having a map on your phone does you no good if your phones battery is dead.

Small first aid kit

Cuts and blisters happen. It is good to have some bandaids, Neosporin and any other first aid items that you might need. If you need medication or an inhaler don't forget them. bandaids work great on blisters to stop the rubbing and help prevent them from getting worse.

Toilet Paper

Restrooms on a trail are few and far between. It is likely that you will need to find a place in the woods to do your business if you are on a long hike.

Whistle

If you get lost stop where you are. Remain calm. Pull out your compass and map and try to figure out where you made a wrong turn. If you are off the trail completely you will need to orient yourself with your map and compass and try to figure out the best way to get back to the trail. If all else fails and find yourself lost in the woods a Whistle can be heard for long distances and can help you summon help.

Cell Phone

Good to have in case you get lost. In the woods it is difficult to find cell phone signal but in some locations if you were to climb to the top of a mountain you have a much better chance of getting a signal which would allow you to call for help. Make sure the cell phone is fully charged and you have an external battery and power cord for it.

Emergency poncho

A small inexpensive emergency poncho (usually $1.50) can be good to have if there is any chance that it could rain.

Flashlight

A small flashlight is good to have if your hike takes you longer then expected and you end up hiking in the dark.

Jacket or Sweatshirt

Good to have in case it gets cold or you get lost

Hiking Poles (optional)

Hiking poles can help you keep your balance in rough terrain.

Camera (optional)

You are going to want to capture the beautiful landscapes and scenery along the hike with lots of photos.

All of the above items should fit inside a regular day pack. If it does not fit then you are taking too much. Think of ways to reduce the size of what you are taking. For instance you don't need an entire roll of toilet paper. Take just enough toilet paper for one or two uses. A good rule of thumb is to only take as much stuff as you think you will actually use. Also try to make your pack as light as possible. Get items that are as small and light as possible. For instance instead of bringing a big heavy flashlight bring a small LED keychain flashlight. It is not as bright as the big flashlight but in total darkness you don't need a strong light to light the trail, besides if you planned things right you should not be hiking in the dark at all. The lighter you make your pack the easier it is going to be to carry it.