Answer 1: I have a few different methods, but the one that appeals to me the most is tying them upright to a tree or pole (preferably semi-naked or naked), with their back to it. There's a ceiling beam (or strong limb, if it's a tree) above them with a rope over it. One end of the rope is around their neck. It's taut, but not so tight that they can't breathe. They can still breathe but it's a little bit of a struggle to get enough air in their lungs to breathe comfortably.
I have a bag with me containing a knife and a gun, more rope, some wire and gaffa tape, plastic bags and a metal whip.
I want to hear the bitch scream because that's what gives me pleasure. I want her to suffer. Her suffering excites me.
I start off slow, sliding the barrel of a loaded gun over her body. I rub her pussy with it till it's wet and then make her suck it, forcing it down her throat till she gags. I could pull the trigger and blow her brains out right there and then, but I don't because that would be a waste. The thought appeals to me though, quite a lot, as I face fuck her with it. I pull the barrel from her mouth and hold it to her head and I whisper in her ear just how much I want to kill her.
I then put the gun away and take my knife out. I want to fuck her with the blade of it, but I hold it to her neck instead and tease her with it, telling her that I'll give her a permanent smile as I run the blade gently across her throat from ear to ear. I then slide the blade down her chest to her breasts and ask her if I should cut them off. Her reaction amuses me. I slide the blunt edge of the knife over her nipples, teasing them with it. Then down her belly to her pussy. I cut her pants off and rub her with the blunt side of the blade. Then I decide to cut her, starting with her pussy, then her tummy, her breasts and nipples. Her wounds bleed a river of red. This sexually arouses me.
I put the knife away and whip her open wounds making her scream and cry and beg. The metal of the whip opens each gash further until she is covered in blood from the neck down. I rub the blood over her body with my hands and feel each open wound. I want to cut her deeper, so I can finger-fuck her wounds. I do that with one, causing her to scream even louder. By this point, with the rope still taut around her neck, her screams sound more like gasps.
I go back to my bag and pull out a plastic bag and a length of rope. I put the bag over her head and the rope around her neck. She fights her restraints, desperately struggling for air. I stand in front of her and pull on the rope as hard as I can forcing it to tighten around her neck. It takes a lot of strength to strangle the bitch and quite a bit of time. Eventually, her body relaxes.
At this point I'm not sure if she's just passed out or dead, so I have to check her pulse and, sure enough, she is dead.
Edit: I forgot to mention the part where I wanted to burn her with a hot metal rod as well. Oh well, you get the picture. Also, if I had a partner-in-crime I would tell him to rape her while I watch.
I know that answer is a bit more than you were probably expecting and reads more like a story, but it is my preferred method, nonetheless.
Answer 2: Yes, absolutely.
There's a saying I like, "there's no thrill in the kill if there's no pain in the game".