A huge part of Africa is still developing, therefore, it is advisable to take certain precautionary measures for one’s own safety.
Though no immunizations are required by law to enter either of the countries, typhoid, diphtheria, hepatitis A and yellow fever vaccinations are highly recommended. It is also for the best to be up to date with polio and tetanus vaccinations.
Make sure you have a soft copy of your passport and a copy in your luggage. Avoid wearing any jewellery and carrying too much cash with you. Be very careful while carrying expensive equipment. Public transport is not too hard to find in these countries, especially in Nairobi, however it is best to not venture out alone.
Read up and make sure you have done your fair share of research about the place before you travel. Travel insurance may be handy in case of contingencies.
These two countries are very close to the equator. The climate here tends to be drastic. It is best to check the weather once before packing. Carry sunscreen, a hat and a pair of sunglasses to protect yourself from the harsh rays. A pair of binoculars will definitely help you in spotting wildlife and the great migration.