Yes, I went on a safari to Kenya years ago. For me, it was a once in a lifetime experience.

Take at least one long lens (300mm plus), extra camera batteries and memory cards (and a strong sunscreen). It's usually very bright, so you'll find that even with a long lens you'll get a good shutter speed (it might even be worth picking up a cheap bridge camera).

Also, listen to your guides and don't wander off (my first night in camp a large lion strolled through roaring all the way and later the van I was in almost got trampled by an elephant).

And if you see any Maasai, don't take their photo unless they say it's OK.

Budget for extras (like balloon rides) and bring something like Imodium for any food emergencies.

It's been a long while (and I was only there a few weeks) but if you have any questions, I'll try to answer them.