Click on the ticket booth and change the ticket price to $5 and press the 'Enter' button. Doing this will give you profit money which you can check at the top right corner of the screen. Keeo repeating to get the desired amount of money.
Below are different ways that you can make money quickly each time you log into your zoo.
Visit Your Friends' Zoos: Your zoo keeping Facebook friends show up along the bottom of your zoo page. Every day you can hunt for treasure in your friends' zoos. Simply click on each of their animals until you've found the treasure.
Visit Your Own Animals: You can also click your own animals to find daily treasure.
Send Gifts to Friends: When they receive a gift the game asks them to send one back to you. You can either keep these gifts to increase your zoo's value (and eventually raise your ticket prices) or sell them to the Shop for immediate cash.
Shake Stand-Alone Trees in Everyone's Zoos: Clicking on trees in anyone's zoo shakes out a bit of cash that, though small, will add up over time (trees that are a part of an animal's habitat won't shake).
Play the Zoo World Lotto with Wildlife Points: Below level 20, Wildlife Points don't buy much of anything. Instead, use them to play lotto on the Home tab. Whether you win or lose, you will still get cash.
Take the Daily Quiz: On the Home tab there's a new one-question quiz every day. If you get the correct answer you get several thousand dollars.
The following is a simple cheat to keep your zoo generating cash and not timing out when when you have to leave your desk or you ALT TAB to a different browser. To do the cheat you must use Firefox and install an add-on called ReloadEvery which allows you to set any browser page to auto-refresh after a specified time. Just right click anywhere inside the Zoo World browser page, select 'Reload Every' and toggle the 'Enable' option.
If you want to level quickly it is best to work through each of the Achievements on the Home page. Try not to spend money early in the game making your zoo look the way you want it to as you will soon run out of cash. If you stick to doing the Achievements in order you'll maintain a steady cash flow. If you keep your Zoo's grade at A you will notice that the top of the Shop page will suggest that you purchase a particular item (e.g., a kiosk). Buy these recommended items before buying animals for your zoo because animals are pricier.