To tame one of those early game you just need to get yourself a slingshot (You can get the engram at Level 5), a low Level Trike (Level 1 - 30) and to be safe around 40 Stones. Then find some Trees and attack the Trike with your Slingshot then use a Hit and Run Technique. It should be much easier because the Trike gets stuck in the Trees and has to get around them. Which gives you enough time to shot him some times with your Slingshot. Once he is unconcious you just have to gather Berries. Use Mejoberries for a higher level after taming. Keep an eye on the Trike's Torpor(You find it in the bottom right hand corner in its Inventory). Once it drops on 0 your Trike will wake up and you have to knock it out again. To raise its Torpor you need to put Narcoberries in its Inventory, click on them and then click on the Remote use item Button (Each Narcoberry adds 8 Torpor). In the Dododex App you can Look how many Slingshot-Shots, Narcoberries and Mejoberries your Trike needs. Good Luck!
I have found that the Triceratops/Trike prefers the tintoberries, my strategy for taming lvl 10< Trikes on a new charachter i usually grab around 40-100 tintoberries and 3 or 5 narcotics/10-25 narcoberries and i use the starve method for around 4 minutes before using a narcotic and putting the berries in!
The trikes are amazing for gathering a huge amount of narcoberries, i ride my Trike to the hills and keep hitting the bushes and then I access the Trikes inventory and grab what i want to keep and then press drop all items for the Trike.
To knock out a triceratops is not as hard as most people think. You don't have to have tranq arrows, a simple slingshot will do too. And if you're afraid of it hitting you whilst trying to KO it, try to get it stuck. Eventually it will even run away from you, as it is not able to hit you anymore!
When ur knocking it out NEVER ever do it on flat ground. Always use a sloped surface as wild trikes cannot climb them. If ur taming a high lvl make sure to bring LOTS of tranq arrows they take forever to knock out. Also make sure you have a a sword or pike ready in case things go wrong(ex: trike regains concious, trike gets attack, or that u just suck). I tamed a female, called it Spencer ;)