>>33407835 (OP)Do you want to murder someone specific, or will anyone do? If the choice of victim doesn't matter then, as the other anon said, the important thing is to make sure there is no conceivable connection between you and them. Travel to a country with strict gun laws. Rent a room that has its own washing machine. Head out into the countryside on foot. Pack a change of clothes, bin bags, and adhesive tape. Don't take a phone or any device with GPS or any kind of wireless connectivity. Find a relatively isolated house at night. Break in. Kill everyone inside. Wash carefully. Change clothes, bag up the bloody ones and seal the bags. Head back to town. Wash clothes once you get back to where you live. Travel somewhere far away, and throw away the clothes (so you don't get busted for traces of broken glass, etc.). You'd have to be extremely unlucky to get spotted.
If you want to kill a specific person you know, that's obviously a million times harder, because the police will figure out that you were the one with a motive and investigate you hard. So you have two options.
The first is the "Jagged Edge" solution: you become a serial killer, kill three or four totally random people in a distinctive way, and then kill the person you actually want to kill in the same way: the pre-established pattern will make it look like they're a random serial killer victim, and the police won't be looking for a motive.
Your other option is to convincingly fake an accident. For example, the Ronald Dahl method.... Invite the person to dinner. Buy 13 oysters. Refrigerate twelve of them very carefully. Bury the 13th one in the soil of a pot plant for 48 hours. Cook the other 12. Before serving, squeeze one drop of liquid from the buried oyster into each of six of the good ones, and serve those six to your victim. Eat the other six yourself. This will give your victim a fatal case of shellfish poisoning, and it will look like pure bad luck - they happened to get a bad oyster.