Summarize this article in one sentence.
Before your hike begins, you should be well-hydrated. During your acclimation stay, you should be drinking 2 to 3 liters of water each day to prepare your body for the hike. During the hike, keep a 1-liter bottle of water in your pack, and drink often to keep yourself hydrated. If there are stops along the way, refill your bottle, even if you think you won't need it. At higher altitudes, your body will burn energy more quickly, so have some snacks such as dried fruit and nuts, fresh fruit, or a bag of chips to eat as a snack.  You will want the snack to be high in carbohydrates, so you can quickly replenish your lost energy.  Beef jerky, chocolate, and hard candies offer good, light weight snack solutions. This is especially important if your hike begins at a lower altitude and increases steadily. You will notice as you hike that you begin to tire more easily, and you may feel short of breath. Take frequent breaks to recover, and go more slowly. Once you have reached an altitude above 6,000 feet (1,828 m) consider resting for a day or two to give your body some time to acclimate. On a long hike, it can be easy to slip into a state where you aren't really paying much attention to how you're feeling physically. However, when you are hiking at high altitudes, you should remain aware of what is going on with your body, especially as you ascend higher and higher.  If you begin to experience nausea, a lack of hunger, a lack of thirst, or if you notice a headache, are feeling dizzy, having trouble breathing, or losing control of your coordination, stop. Tell another member of your hiking group. Don't ignore these symptoms, as they may be early signs of altitude sickness.  Don't try to tough it out. These symptoms may subside quickly with a bit of rest, but they could also turn into something more deadly if you aren't careful. If and when you start to notice some shortness of breath, stay alert. Focus on taking deep breaths in and out, and make sure that the breaths are even. This will help you avoid over-exerting yourself. If you feel that you are over-exerting yourself, stop and take a break for a few minutes to regain control of your breathing. Each time you ascend another 1,000 feet above the altitude that you live in normally, you should stop and rest for 2 hours. This will give your body a chance to acclimatize, and will help you avoid dangerous consequences of ascending too quickly. This may mean taking more time than you hoped, and may mean camping over night, so be prepared for this reality. If you are on an overnight or multi-day hike, you should not sleep at an elevation that is more than 1,500 feet higher than the elevation at which you slept the night before. For example, if you slept at 6,000 feet the night before, you should not sleep above 7,500 feet the next night. With high altitude hiking, it is important that you be ready to turn around and call it quits if any of your hiking group begin to experience symptoms of altitude sickness. It may feel disappointing, but it is better to be safe than stuck on the top of a mountain with a person who is suffering from severe symptoms of altitude sickness.

Summary:
Stay hydrated. Have snacks to keep your energy levels consistent. Climb slowly to prevent burn out. Remain aware of your physical condition. Focus on deep, even breathing. Stop and rest every 1,000 feet above your normal altitude. Avoid sleeping at altitudes that are too high. Be prepared to turn around.