I'm guessing it has to be someone who has wronged me in some way. So I would wait a fair while (six months at least) before I killed them so it looks like I don't have enough motive to do something like this. I would also do extensive research, I would follow them and find out if there were any times that they were alone and vulnerable, and any places that were deserted enough to let me jump them.
While this research is being done, I would buy all the supplies I would need (even if I already owned them) and I would use cash. Some of the supplies would be boots, cloths, gloves, sunglasses, a hat, grass seeds, a shovel, and some other odd stuff. I would also find a place to bury the body, it would be a location that would at least be a hours drive away from where I lived, and somewhere people rarely go (cliche bush lands). And I would check there was absolutely nothing wrong with my car that could draw attention.
Now I would jump the target at my planned secluded spot, I would hit him in the head with a bat or strangle him from behind (I would prefer to strangle and not get blood in the car) and dump him in the boot, and thrown away the weapon somewhere close but not to close. I would drive calmly and normally until I had almost reached my dump spot (about 10 minutes walk away) and carry the body the rest of the way. I would dump the body in the pre-dug hole (at least 1m deep) and begin to fill it, sprinkling the grass seeds over the spot and the area to encourage grass to cover the freshly turned earth, and drag any leaves or foliage over the spot as well.
I would trek back to my car where I would change out of my spare cloths, boots, gloves and all that stuff and place it in a bag. I would then start driving back home and would find a river, place rocks inside the bag with all the equipment/cloths and throw it in a river (a fair distance away from dump spot A). I would then go home, have a shower, and then head to a friends place to work on having an alibi on the chance that people did come asking questions.
Alternatively, knock on my targets door, push them inside, and proceed to strangle them (kill them in any way where they won't bleed). I would go back to my car and bring back a bag of supplies which would contain a tarpaulin, duck tape, saws and blending appliances. I would duck tape the tarp to the floor and then cut up and blend the body until it is in small enough pieces to wash down the bath. Clean up, and casually leave.