Apart from filling in a visa form (recommend you download it ahead of travel and fill it in at home in peace and quiet!) and paying for it, you will need to fill in an INDIVIDUAL GREEN IMMIGRATION FORM which is in addition to the visa form. You need ONE FORM PER PERSON and not one form per family which is what British Airways staff told us when handing out these forms just before landing at Nairobi. This misinformation cost many travellers a lot of extra time having to queue up again and lead to some stonewalling from the immigration officials - not the best way to end a long flight especially in the heat and humidity of Nairobi airport!