1. Build all available kiosks and upgrade them
In the beginning it seems that you have too little space and too many different buildings. Maybe, but you should still build all the kiosks and upgrade them as quickly as possible.
This will increase your bottom line and make things much easier in the long run. I know that $ 1 profit per kiosk sounds ridiculous, but the sooner you start doing it, the better it will be later.
2. Focus on time-limited missions
Periodic you will be given a mission at a time. They should be your main focus due to their limited nature and rewards, which are usually very generous.
3. Choose which animal you breed
When you breed two animals, you can leave everything as it is and hope for the best, but of course it is better to choose a more specific species.
It's worth it, especially if you want to get a specific animal for a specific habitat or when you want to open all the question marks. If your zoo is full and you just want to breed animals for sale, then you don't have to bother.
4. Catch butterflies
If you want to level up faster, collect more coins and even premium currency, just start visiting other zoos and catch butterflies there.
Usually there will be one butterfly in a zoo (sometimes two, sometimes zero), and it doesn't matter if you like the zoo or not. Just try to visit as many zoos as you can, because the more butterflies you collect, the better your rewards and chances of earning premium currency.
5. Remove trash only when receiving missions
I learned this lesson: always leave trash around you, because you will be constantly given missions to clean it up. Do this only when you receive missions and your level will rise much faster. You will even get a cash reward for cleaning.
6. You can skip missions
If the completion of a task turned out to be too difficult for you, or you just do not want to do it now, you can click on the mission and completely delete it. Then a new one will appear in its place. But my advice to you - if you want to pump your zoo faster, try to complete all tasks.