Most pilots are used to setting the mixture to full rich for takeoff and landing, a procedure that maximizes engine power and facilitates cooling at lower elevations. However, at altitudes above 5000 feet, maximum power is achieved by properly leaning the mixture. This should be done during a run-up at full power. If an EGT gauge is available, the mixture should be steadily leaned until reaching the hottest point on the hottest cylinder. Then the mixture is steadily enriched until the temperature cools by 50-100%, depending upon the recommendation in the POH. Engines with fixed-pitch props can be leaned to maximum RPM. This setting should be used for takeoff and initial climb out rather than the full rich position used at lower elevations. As altitude is gained, further leaning will be needed in order to maximize engine power, a process that must be reversed during descent and landing. At pattern altitude, another maximum power mixture adjustment should be made to ensure maximum power availability in the event of a go-around.

If you don't have more than 70% of takeoff speed at the halfway point, the takeoff should be aborted. On sloping runways, 100 vertical feet is equivalent to about 50 knots of true airspeed. Many airports in the mountains will have recommended departure procedures that provide the safest corridors through rising terrain. If such procedures can’t be found on the airport website or at the FBO, local pilots are usually a great resource. If no information is available, it’s generally a good idea to fly away from the leeward side of a mountain or ridge and to seek a pathway offering very gentle turns to keep loss of lift at a minimum. 

Landing at short mountain strips requires exact airspeed control to eliminate float. A 10% increase in the proper approach speed results in a 21% increase in the landing distance. In an emergency, land uphill and carry a little extra speed for the flare.