Coming from Doha, go straight on Khalifa Street towards Education City. Continue straight, pass Education City (on left) and at the Bani Hajer roundabout go straight.
You will continue on this road for some time, and will pass Al Rayyan sports stadium and a petrol station on your right. Sheikh Faisal's farm will actually be on your left on the other side of the road, but since there is no left turn, you have to continue past the farm in order to make a U-turn.
You will soon come to the Shahaniya round-about (its an overpass, you stay to the right to go up.) Make a U-turn at the roundabout. Soon after making the U-turn you will see signs for Sheikh Faisal Bin Qassim Al Thani Farm, and you turn right where the sign indicates. Continue straight after making the right turn and you will see the museum.