The number one way to thrive at altitude is to respect the time it takes for acclimitization.
Start low: Moving from sea level to a sleeping altitude of over 9,000 feet in one day hinders the body’s ability to acclimatize. Instead, spend a day or two between 8,000 and 9,000 feet before moving higher.
Take it easy: Don’t go crazy on your first day at altitude. Give your body an adjustment period with mild exercise, and then ramp up your exertion level over the next few days. How much altitude you should gain each day depends on how you’re feeling: shoot for a moderate challenge on day 2, and feel free to push yourself on day 3 and after if you feel good.
Climb high, sleep low: Where you sleep is an important factor because your oxygen levels are lowest during the night when automatic (slower) breathing mechanisms take over. If possible, sleep more than 1,000 feet lower than your highest point reached during the day. Been ascending all day? Consider hiking uphill after making camp, gaining a few hundred feet, and then returning to sleep.
Take a breather: Stop to rest every few days to recover from altitude stress.