Complete Contract Hunts if you need money. They are fairly easy to complete.
Targeting
Aim for the lungs or heart to get a bonus reward at the end of a level. Lung shots are worth $25 and heart shots are worth $50. This is done easier with the help of the Infrared enhancement to your rifle scope which shows you exactly where the lungs and heart are located when zoomed in. Shoot the body parts marked in red on single target dinosaurs to make it flinch and allow you more time to reload and check your position. This is very important while hunting large dinosaurs such as Tyrannosaurus Rex. To take down predators efficiently, wait until they leap on you to get a clear shot on their heart, lungs, or brain. Make sure you can defend yourself if there are several of them around. When hunting herbivores, carefully aim your first shot. Most herbivores, with the exception of Triceratops and Stegosaurus, will flee quickly when injured. Use the assault rifle to take down small and fast-moving omnivores. It is more important to have a weapon that can quickly pump out rounds at the fast moving targets instead of relying on power and zoom.
Upgrades
Your base weapons will only be useful until you reach the second region. At that point, you will be offered the only chance to spend money instead of gold at the store to purchase a new weapon. Do not focus all weapon upgrades in one specific area . Keep the Power, Ammo, Zoom, and Balance equally upgraded in order to maintain access to future missions.
Various Google Play Achievements
Achievement
How to unlock
241 (1,000 XP)
Kill 2 Dinosaurs with 1 shot.
Both Barrels (2,500 XP)
100 Kills using a Shotgun.
Brain Game (2,500 XP)
25 Brain Shot Kills.
Broken Bones (5,000 XP)
Kill 200 Dinosaurs in Boneyard.
Deadliest Catch (1,500 XP)
Kill 100 Dinosaurs in Deadly Shores.
Extinction (10,000 XP)
Killed Everything.
Guns Blazing (2,500 XP)
100 Kills using an Assault Rifle.
Heart Attack (2,500 XP)
50 Heart Shot Kills.
Jungle Warfare (2,500 XP)
Kill 150 Dinosaurs in Jungle Mists.
Smoking Barrel (5,000 XP)
100 Lung Shot Kills.
Straight Shooter (5,000 XP)
200 Kills using a Rifle.
X-Ray Vision (5,000 XP)
75 Kills using infared.
Weapons
Purchase one weapon for every region. This is also a requirement for trophy hunts. You should not have any problems having enough money to do so. After reaching a specific upgrade level for a weapon part, you must wait for its delivery. Hunting requires you to arm yourself with two different types of weapons. For your primary weapon, use a long-distance gun with top firepower. The goal is to strike down your target before they get too close. If you need to do a second shot, make sure you have a secondary weapon that can kill your target when it is in close range.
Money...