Well, it is easier to find a high spot where you can over look anything around you first. Then look on your map (radar is helpful) then call out with the call. If there are any dots in or around the circle around your person they will eventually come closer and call a response back to you. When you see one, take out a gun, double barrel and x bow are good to use. Then when they get close shoot one. It may take 1-4 shots to take it down though. You should shoot around the head, the chest or the stomach.
If you stand still the t-rex may not see you, but if he raises his head up he is smelling.If he raises his head completely down, start shooting...... Cause he found you.If he raises his head back to the normal position he didn't find you. P.S.-Use the sniper rifle cause it aims better.
T-rex are not good that they can spot you easily. Weak spot for them is around their eye. Here are the tips for hunting them:
1. T-rex sometimes stands up high looking for you, it roars like the sound of a Ceratosaurus if it spots you.
2. When it is far, use a sniper, but when it is running towards you, use a shotgun (I recommend a double barrel shotgun)
3. Look at your radar, relocate to the sea or lake where the T-rex is on shore and call it, then it will swim to you, then shotgun of any kind will work.(Doing this on RAVAREN'S BRIDGE is much easier.)
Go in any map as long as you get to a high spot.Then pick 3 guns at the least. You want to try to hit it in the middle of it's 2 eyes.If you get a direct hit it will kill it in one or 2 shots depending on the size and accuracy.