From experience, three key things to focus on when taming: 1.) Always bring 400-500 extra narcotics and tranq arrows/darts. 2.) Never put kibble in a dino's inventory. 3.) Lure it away from any water. When it is knocked out, give it 1 narcotic every 2-3 seconds and every 5-10 minutes, look around and check for any hostile dino's.
I dare you to raise one!! They are savage if you got two high lvl parents (about lvl 140ish) and you get imprinting on it. The thing will become an adult with about 230% melee and basically one chomp any bronto!!! But on the down side you loose your job and your girlfriend
Make 4 metal dino gates and 1 large bear trap. Place three frames and door into an incomplete square and the large bear trap in the I between them. Lure the Giga into the trap and while its trapped place 4th down to make the square. Then just light it up with tranqs