Mountain air is dry, and you will lose moisture just breathing. As a rule of thumb, you know you are drinking enough if your urine is clear. Avoid tea, coffee, or alcohol. They promote body fluid loss through increased urination and promote dehydration. Eat high-carbohydrate foods.
Carbohydrates produce energy faster than do fats.
Also, the metabolism of carbohydrates requires less oxygen. Avoid sleeping pills. They can cause shallow breathing while sleeping, making it harder to get enough oxygen. Smoking also makes it more difficult to get oxygen from lungs to tissue. Although you can't take a pill to acclimate to altitude, you can take a prescription drug that can reduce the symptoms of altitude sickness.