Heyo! Here are some tips I have for challenge mode.
1. Do not sell your dinosaurs. In challenge mode, the hammond lab rises with the star rating of your park, and often starts when you have at least one dinosaur in your park. By selling your dinosaurs, you get a quick profit from selling them, but the hammond foundation won’t go down and will eat your profits. Leave the dinosaurs and aim to grow a sustainable variety before you think about selling them.
2. You just need 1 dinosaur to be visible to start earning profits. So you could build an exhibit and place in a single dinosaur from the pack that you got. The other dinosaurs that are in the wild, tho not visible, will add to the profits.
3. Like how you mentioned, contracts are a great way to earn an income. Avoid contracts that requests of you to reach a certain star rating, facility rating, or overall dinosaur rating as they take too long and the rewards are not that helpful.
4. When you reach 1 star, research the dig yield upgrade and apply them to the lab asap. That would increase your chances greatly.
5. Carnivore and Sauropod fossils sells really well, so if you are not getting much in terms of extra treasures, amber from these dinosaurs would sell up to $100,000 each, you won't lose the chance to get the dinosaurs to reach 100% as you will only be allowed to sell a limited number of fossils per species.
6. You do not need to genetically modify dinosaurs early on. The costs to incubate dinosaurs with added genes would lower the chance of success and would take a lot of money than their base form. Aim for social numbers and variety until you get a good enough of a profit. Do acquire 100% genome, as those dinosaurs cost the same but live longer and are rated higher.
8. Aim for herbivores than carnivores as they do not eat your guests. If you plan to have carnivores, avoid attack genes, as the attack gene is what speeds up a dinosaur's breakout. And if you could modify comfort genes, aim for 60% or less for carnivores, as that is the sweet spot for them not breaking out during storms, tornado attacks are still dangerous.
9. Restaurants, clothes shop, arcades, and restrooms are the only guest needs buildings you need that cover fun, food, drink, and restroom, so no need for gift shops, fast food, bowling alley and so on. Transport and hotels are also essential so leave some space for them, and aim to get storm stations in your park once you have acquired them.
10. Do put in scenery items in your exhibits, as they boost a dinosaur's rating ever so slightly. They do not cost much and they don't raise it too high, but it does help you reach higher star ratings asap.
11. The best greenhouse combo I use is: Horsetails, Paw Paw (or mosses), Ginkgo, conifers, and rotten wood. However, do not think about using the greenhouse in the game early on in jurassic mode, as the costs of the plants, feeders, research, and growing the plant would reach the millions.
So far these are some tips I could provide, but I am certain you would win Nublar North Jurassic Mode!
