All types of ranged attacks are viable so long as there are indestructible debris or walls to take cover behind, and timing is executed. For the demon in Lost Izalith, where no cover exists, one can simply strafe back and forth between shots, since its lightning bolts do not track you.
In Undead Parish, the player can lure them to the top of the lower stairs to render their horizontal sweeps useless.
In Sen's Fortress, a Rusted Iron Ring is highly recommended as the boggy ground will greatly impede movement. In addition, when players reach the upper sections and use multiple ledges to safely descend to the location of the Titanite Demons, they may successfully perform a drop attack.
In Anor Londo, the player can run into the room occupied by the Titanite Demon and then quickly exit, in turn triggering the demon to move closer to the entry door. The player then can freely take out the demon with ranged weapon from outside the room.
A somewhat reliable melee approach is to position oneself behind its free arm, where it appears to be missing a leg. Its close range attacks will miss allowing the player to score a hit or two. Its tail can inflict minor damage, as it swings it in conjunction with its weapon. Remaining in this spot or behind the demon for too long will trigger its jumping attack.
Alternatively, forcing oneself under its left arm will cause most of its attacks to swing harmlessly overhead if the player is far enough to the right or low enough during his/her attack animation. This does not trigger its jumping attacks. Its second attack can, however, be easier avoided if the player moves to its center by the leg. The pole jab, the third in its attack pattern, then requires the player to move back near its arm in order to avoid damage.
The pole-grab attack can be used to the player's advantage by moving either behind its right leg or left arm.
The Titanite Demon in Lost Izalith is considerably stronger than other Titanite Demons. It is also the only Titanite Demon that respawns, making Lost Izalith the only place possible to farm Demon Titanite.
The Titanite Demon's jumping attack is able to hit multiple times when it lands on the player, as the player can get hit by both its weapon and its body. On NG+, this makes it capable of dealing over twelve hundred damage through a full set of heavy armor.