Just ride your tapejara,take your best comp bow,calculate how much arrow you need,take arrows,follow the titan and change your seat and shoot,after some time it will be stuck and that's your best time.shoot at will.you've killed a titan.I've killed 2 titand in 1 ark day in this way.
Easily killable with a wyvern. Lightning and poison easiest down to longer range in attack. Just hover above and light it up :) killed my first today and it didn't touch me once. Just remember to watch stamina ;)