I've done some fairly high altitude mountaineering. Have also done some high-ish altitude climbing. I've used Diamox with success when getting to higher altitudes.
Tips all depend on what you're doing. There are plenty of high altitude walks out there. Heck, the route that almost everyone takes to summit Denali is just a long, slow slog with no technical sections.
My most serious mountaineering and alpine climbing has all been done at what would be considered fairly low altitude. I have no interest in spending time in the Himalaya. It's just not my cup of tea, and I've accepted that.