I have the dawnguard dlc and I am trying to be creative of all the ways I can kill a vampire. Can I have some tactics/tips for killing vampires like strategyes to kill vampires

Don′t underestimate their Drain Health spell, like, ever.

Use Dawnguard weapons against vampires because they do additional damage against them. Try sneaking up on vampires with melee weapons or use a bow/crossbow from a distance to pick them off.

PS: Always carry potions of cure disease with you. It's easy to contract Sanguinare Vampiris when you're up against vampires in a fight.

Since vampires are weak to fire, and need magica for their draining-spell:

The Flame-Atronach, the Storm-Atronach and the Dremora-Lord with his fire-enchanted sword are usefully.

To prevent vampires to raise undeath, you may just raise them before.

The turn-undeath-spells from the school of healing may stop them from attacking.

Vampires like any other enemy in the game are vulnerable to weapons, try hitting them with a sword or axe.