This will be a short, completely hypothetical, post.
What do you think is the most practical method of murder? I would never kill someone for the sheer fun of it. I don't get any rush from the thought of gore, pain or torture, but I would murder if I had to.
The hypothetical is that you have to kill someone before they ruin you. What is your method? No specific limits or rules, but they must result in you getting away with it. Think of it as self defense in the philosophical sense, rather than legally.
Mine would be and always has been poison. Very little forensic evidence (unless they know what they're looking for), depending on poison it can take a lot of time to work , you don't get your hands dirty. Depending on your locality, different poisonous plants will be available, however, independent of locality, poisonous plants will always be available.