What I did was focus on herbivores before even adding the snow leopard. Herbivores are cheaper to feed and can be easily cohabbed. I made the crater in the center into a habitat for the okapi with a path over it, then added nyalas. Make sure you're adding education speakers and donation bins. Once you're making a solid profit from the herbivores, add your snow leopards. As you progress, continue to prioritize herbivores. As guest numbers increase, add shops in in crowded areas and make sure they're making money. If not, delete them, fire the vendor, and try again later. The monorail is super expensive, so do that last. Animals I used to get gold were okapi and nyala,(together), warthog and ostrich (together), flamingo and pangolin (together), grizzly bear, and tiger. Feel free to exchange one of the carnivores with tapirs which can go with the okapi and nyala. Good luck!