Zoo Tycoon 2 DS is a fairly simple game, once you settle on a few techniques. This section will give general pointers that should help you to go far within the game.
Build cages quickly and efficiently.
Immediately after starting, you should determine where to set up a cage or two, and then you should put in some animals. This is the fastest way to boost your zoo ranking so that you can take advantage of other options, something you'll want to do whether playing in freeform mode or completing campaigns.
Use your maintenance staff well.
The most important staff person is the general zookeeper. You should place one within a cage whenever you have animals there, since this wonderful individual will help take care of animals. If you don't have one positioned, that task falls to you (something you can't possibly keep up with alongside your numerous other duties).
Don't waste money on too many of a given breed.
Unless you're in campaign mode and it specifically says to do so, don't place more than one or two males and one or two females within a given exhibit. The additional animals don't have any serious benefits, and you can get more animals in each exhibit just by letting a male and female breed and produce offspring.
Keep your animals happy in their biomes from day one.
The tricks here are to instantly place the animal's favored soil, such as Sahara or tundra turf. Then add in a dwelling place (if that animal likes one) and a play toy (if appropriate). Next, add a patch or two of water and then possibly some shrubbery. Some animals like less of this than others, but in general the above works about right. Finally, make sure that you go in zookeeper mode immediately after placing animals and play the game that will improve their mood. It's the number-tapping one. If you do this with each new animal you place, you'll improve their attitude and people will be happier with the exhibits.
As soon as your zoo hits three stars, make sure that you're investigating new breeds of animal. It's also immediately worth investing in more buildings. Investigating structures allows you to build a compost area (for some extra revenue) and a better eatery, both worthwhile. As far as your maintenance people go, it's usually worth researching three times, so that they become better at animal husbandry. Once you have numerous breeds established with well-educated workers, you can sell young animals born in captivity to earn a little extra money (or free them into the wild to boost your zoo's rating).
Keep the above strategies in mind at all times and you'll have little trouble meeting any of the challenges the game throws your direction.
NEXT: Campaign Walkthrough