For your first time to Kenya , you may want to book with a reputable company from your home country, that way you are guaranteed to get what you have paid for. Check for recommendations from multiple sources before you book and if booking with a Kenya based operator, and go with one that is a member of KALTO (Kenya Assosiation of Local Tour Operaters} . Whilst you are on safari then check out the other tour operators by asking fellow travelers in the lodges you stay at or your beach hotel as to who they used and what was the standard to their safari. Then you will be equipped for your next trip.
Other travellers would like to do it privately. Kenya is now back to business from the very reasons
you know so the Kenyans can enjoy the fruits of tourism without needing to be in KALTO. It's better for the travellers to be given the chance to choose what
they think is good for them, so then competition will be heathy.
