The temperature is 25% higher than normal, water is extremely scarce, grasses are relatively abundant, although they are not edible for humans. The air is only half the oxygen content that it needs to be for humans. Gravity is 2.11G and air pressure is 75% of what humans require
Ah, here we go! Right up my alley!
Temperature... I would replace the hair on the head with feathers, possibly silver. A thick coat of feathers is much better at losing/gaining heat than a similar fur coat, so it'd stop overheating of the head. Long fingers could also help increase the surface area, as fanning with a larger hand would also help with the hand losing heat.
Water... Uric acid instead of urea. The genitals would need to be modified to be able to do this, but we'd save a lot of water. Better panting ability and wilful sweating might be of use, too.
Oxygen... Larger lungs are an obvious choice. Perhaps increase the amount of mitochondria, so it's got more efficiency. An avian lung would vastly improve breathing.
Shorter, stouter limbs are a must. Improving shock-absorbing would help, and hollow bones (which could fit into the avian lung system) would also reduce weight-to-volume.
Air pressure... Well, better breathing helps with that. Other than breathing problems, low air pressure doesn't affect humans much, it's just moving between the states that's the problem.
Most of these solutions are either relatively simple or can be taken from an average bird. Should be a relatively easy job, since we have plenty of resources.