LionHunter has given you some good advice. There's good and bad taxidermists eveywhere in the world and the internet means they all have access to similar supplies. (FWIW) The best taxidermist I know of in Africa is Lifeform Taxidermy and the best I've seen in the USA is Buckshot Taxidermy in Texas.

As LionHunter also says, you need to do a lot of careful research, but I'll add that you shouldn't restrict your research to taxidermy work alone. The truth is that most people don't really know what the live animals should look like or how they stand and move in the first place, and without knowing that, you can't know what your taxidermy work should or shouln't look like.

Therefore, you need to start by watching wildlife documentaries etc very carefully and pay especial attention to how the animals stand and move etc. - How they stand is especially important. For example, another forum recenty had a thread where a guy was dead chuffed with a fullmount trophy and posted pics of it and got all the usual wows, oohs and ahs etc.......... no-one (except me) noticed that the way the animal was standing was completely wrong........... So first start by watching the live animals (hell, even watch your cat or dog to see how they stand and move) and then go look at websites and studios etc to check out their work at every opportunity.

As Lionhunter also says, the biggest challenge to a taxidermist and the easiest to get wrong are the cats. Esp Leopards, so if the taxidermist can get those right, they're usually gonna do the rest right as well.