My 02 cents
1) In the situation described you need every bit of power so do full power runup and lean to max RPM or MP. Don't enrichen the mixture a bit leave it at the max power setting you can't hurt the engine and enrichening he mixture will reduce power
2) Lifting off is only the first problem you face. The next and equally important issue is how will I climb to a safe altitude to proceed on course. You must have pre- planned climb out flight path that will take you over level or preferably descending terrain for your climb out. If you are in a valley airport plan to climb on the windward and sunny side of the valley where there will be rising air
3) Flukey winds are often caused by localized thermal activity near the runway. Waiting a couple of minutes before starting the takeoff will often turn that tailwind into a head wind
4) Finally takeoff planning starts with landing planning. Most light aircraft will use significantly less distance for landing than takeoff particularity in a hot and high context, so before landing you need to have already thought about how you are going to do the departure