Have an extra cross bow if using primative, bring extra tranq darts, or arrows. And bring someone to help it will make it much easier. Once you start to tranq out do not stay close to water, once rex is nearly knocked out it'll try and run from you if your close to the water it'll go there where it'll be nearly imposible to tame. Most importantly have fun, be kind to others!
I have figured out a new way to tame dinosaurs cut off the dinosaurs meat wise in the area try and keep the dinosaur in the area and send a dodo bird out to attack the tea Rex with bunches of Botox in and it had the tea Rex eat the Botox and it’ll knock it out you go feed it meet make sure you have plenty of Botox in and you’ll have a pet your ex and no I would not recommend trying this whenever your level one side effects may be dead dodo bird hey might find you and run but seriously You better find a good hiding spot