[Swoop]

If you're one-on-one with a hunter, it's generally not too hard to take out as an affliction warlock, depending on your gear. (as an example, you can see my gear from my profile on the left)

The biggest thing to remember is that generally their melee is nowhere near as good as their ranged attack, so get in close as fast as possible. I'm not sure of your level, but if I just want to kill a hunter quickly, I won't hold back on cooldowns. I drop curse of weakness on the pet, and siphon life. Cats are generally fast but low damage hitters, so a CoW really drops their dps down. Since they're both instant casts it only takes me a moment to cast, and I can do it while I'm running towards the hunter.

Send your pet straight at the hunter and don't stop it attacking until the fight is over.*

*Note: If you use the succubus, send her to seduce the hunter rather than attack; this will give you some time to deal with the pet, and use a normal fear. If they trinket out of the seduce, even better; they've probably just wasted the only, or one of two, protections they have against fear.

As soon as I've dropped those two dots on the pet, I deathcoil the hunter, which usually gives me time to get in close. (assuming no resist) If you have instant howl, then use it once you're in range of the hunter; I probably wouldn't recommend trying to get a normal fear off with the cat pet beating on you, as the hunter will get range on you while you're being interrupted by that cat. While they're both (hopefully) running around feared, drop either an unstable affliction (if you have it) or an immolate, and then run after the hunter, keeping in melee range.

If he resisted fear, don't worry about the UA or immo, just drop your three dots (corruption, Curse of Agony, and Siphon life) and keep running in circles around him. Most hunters kind of panic when you're in their face. Watch out if they FD as they've probably laid a trap. Make sure to circle around the spot they FD'd in rather than running over it to stay with them.

Rinse and repeat whenever your dots run out. If you are feeling confident, try a drain life or two. For example, when they're lower on health, I like to pop the AB trinket and then drain life them, or better yet pop a normal fear on them. If it takes more than 40 seconds for them to die, then pop another instant howl if you have it.

Using these tactics, I can generally kill any hunter I come up against one-on-one. Once I get two hunters on me though, it's generally goodbye warlock. However, I haven't been in that situation since the new talents, so instant howl may be a lifesaver and give me a chance to kill them. (I really hate hunters, my partner laughs every time I swear about them)