What are some ways to prevent (mountain) altitude sickness?

Be Cautious: Climb slowly: let your body acclimate climb high, sleep low—sleeping at lower altitude then you have spent the day hiking lets body adjust hydrate if ill with headache, nausea, irritable, feeling hung over—go back down. Altitude can be fatal. Consider Diamox (acetazolamide) to prevent altitude sickness—talk to travel/ wilderness provider. It does not make you bullet proof ; still respect signs of sickness.