Welcome to a great forum. I'm a new guy, just made my first trip to SA last spring. Here are couple of things that pop into my mind (some have already been said):
Wear your good, worn in boots on the plane and change into slippers on board. That way if your luggage gets lost you still have the most important part of your wardrobe that can't be replaced en route.
Start working out now, you are going to walk, crawl and slither a lot if your hunt and outfitter are any good.
The animals in your package are not guaranteed, they are just included if you get the shots and kill them. Start shooting now, and do it as much as you can. Most PH's try to get you in to less than 200 yards for your shot.
If your PH says "That is a really GOOD (fill in the blank), you need to take it", do it if you can afford the trophy fee and even if you can't.
If you plan to use the outfitter's rifles take an ammo pouch with you to put on your belt. It would have saved me from an embarrassing experience I had taken one.
Keep checking in here and asking any and all questions your have. Folks here are really helpful.