Tease damage is usually ineffective against animals, elementals, other characters' summons, and ghosts. Otherwise I find it usually very effective, and most corrupted enemies are vulnerable to it, so it comes into its own in Act 2. I used the power 'Seductive Sway' against the Lureling last time I played and dealt over 1000 damage with that single attack, and my tease build and Arona's holy damage set made very short work of Alissa in Dracia.
At level 6 I'll have Seductive Sway and Dischord as my slotted recharge powers, which cover most situations, though I might switch in Allure/a non-tease single-target attack (I'll have to find a new one now spells and charms are split out) if I know that what's coming will be weaker to or resistant to tease. Sexiness and leadership both benefit from Presence so teasing and summoning fit together well. Then use your equipment to boost leadership and temptation.
Azyrran's sleep buff converts all tease damage to pheromone damage, which I find much less reliable, which is a shame 'cus she's one of my favourite companions otherwise.