With a storm I find that using ultimate while the titans back is open seems to do a lot of damage besides that fireballs are your best bet
Titans take damage now no matter where you hit, and you do way more damage hitting them wherever they are burning. They also changed the mechanics of the fireballs they could conjure up right on top of you and get you seriously rekt. They are much easier to dodge now. Group of 4 on a legendary mission and we took down 3 without 42 wipes and seeing the dead ones respawn. They fixed that too. If you fight a group of 3, kill 3 and wipe, those 2 stay dead where before they were back up.
weapon: long range
elemental attack: mine were fireball and lighting
component: increased elemental attack and shield
strike titan arms when its glow (preserve ammo)
aware surroundings and kept on dodge/dash (dodge TITAN fireball at the right moment when it get close 2 u)
keeping distance should keep you safe from TITAN firewave attack.
in the last moment of TITAN lifebar, it will go rampage and use every attack it has, this time just fly away surround it 'till it die itself.