You have some very good advice in the earlier posts. Which can mostly be summarized as "take what the bush provides."
If you like to plan and research (and if you are on this site asking questions, you probably do), here is a suggestion I started a while ago.
Step 1, communicate with PH about where you are going and what's generally on each property. They almost always have surrounding properties they can go to if you are looking for something specific, so understand what's in the area as well.
Step 2, make a list of what you have already shot, and don't want to shoot again. Some guys will take a nice kudu every trip. Nothing against kudu, but I wont. Make sure your tell the PH what you are not interested in, and they will tell the trackers on the back (more on that in a minute).
Step 3, make a primary species list (e.g. I really want a Nyala, Klippy, White Springbuck) and communicate those priorities. The 3 species I used as examples are all found in very different places, and you will have to go look for them. That takes time. You are not going to find a Klippy looking for a Springbuck - they are not neighbors.
Step 4, make the "I know these are found here and if we see a good one, I'd be interested list." For me, this includes everything that I have not previously hunted. Everyone should have there own list.
Step 5, decide for yourself what kind of animals you are looking for, its very personal. I don't even own a tape measure, and since I have never actually seen a Cape Grysbuck, I have no idea if its a good one or not, so I go by what the PH recommends (and I only hunt with PHs that I have confidence in). This is a very important step. Many guys do not like to admit that they are trophy hunting, but many are. If, when you get home and are sitting alone in your sitting room looking at your animals and you will only be happy if they are silver/gold medal, you need to tell your PH that you are only looking for silver/gold medal animals. You might not get them, but if you're not going to be happy with less, you need to say so before its in the salt. On the other hand, if what you really and personally like are old animals that are worn down and roughed up (that's me) say that as well. This is a very important and often overlooked step, and what often happens is this: the conversation with the PH is that you are really looking for a top class Klippy, but you're hunting the Eastern Cape. He says that going to tough, but we will try. Then he mentions that since you are in the Eastern Cape, what about hunting Vaal Rhebuck instead of Klippy's. Turns out its a very similar hunt, and the Vaallie's are huge in parts of the Cape. Instead of spending time on something that's not really going to be in the area you are hunting, you can get a great animal that most others have never even heard off. Communication!
Step 5 (keep in in we are still in the planning stages at home), set a budget for yourself. I'm only going to spend $xx,xxx.xx on trophy fees. You still have to get them home, etc. You can hunt all four Springbuck in the Cape for about the cost of a Caracal. In African horn dollars, the Springbuck are the better value but a Caracal is a Caracal. Where you get into trouble is when you are 3 Springbuck deep and a Caracal opportunity presents itself. Ok, that doesn't happen often unless you are trying, but it can happen.
Then go and have a good time. There are about 45 huntable African species in RSA alone (this number varies depending on if you count designer species like black Impala, Golden Wildebeest, etc?). So, there are a lot of animals to look over. Focus on a smaller than anticipated list of "primary species" and then be flexible on "what the bush provides."
Lastly, the trackers and other guys on the truck tend to be very rote. If the PH tells the trackers "we are looking for Nyala," you will only see Nyala. You might drive by a world record Oribi because you were only looking for Nyala. That's the reason for Step 2. It happens a lot. You have to communicate.
These are just some thoughts. Everyone should make their own their own. It starts with communicating.
