For most of us who live at or near sea level there is not much you can do in advance to prepare for a trip, apart from arriving early. It helps to be physically fit, but some people just seem to acclimatize faster than others to reduced levels of oxygen at higher altitudes.
If you are known to be a slow acclimatizer, and have had problems in the past, then Diamox is a proven preventative option against altitude sickness. In truth, we all get the odd headache, but the key is to allow enough time for your body to adjust before climbing high, ascend slowly, drink plenty of water and suck in deep breaths.
On all our expeditions we carry Diamox, Dexamethasone and oxygen. We are also tested in dealing with any issues related to altitude and rarely experience any serious problems. If we do, we will administer the only fool-proof treatment we know: to descend. So, don't over-think it. Seemingly more often than not, it is all in the mind.
Welcome to the team. We look forward to meeting you.