Assassinations are the result of planning and preparation to create opportunity and then the application of chosen means. It is certain that the first strategies used were direct and simple: find the leader and stab, strangle, suffocate, defenestrate, decapitate, rend, drown, or bludgeon them to death.
The first assassins may have used flint. This would have occurred only in close-knit groups where security was not thought needed, such as amongst nomadic or early sedentary peoples in Mesopotamia where disagreements would be solved with vigilantism (i.e. ‘mesopotamocide’ — however it is important to note that information from this far back is very sketchy and debatable in nature).
As civilization took root, however, many leaders began to have greater importance, and they would become more detached from the groups they ruled. This would have bought planning, weapons attached to long sticks, and subterfuge as major factors in successful assassination.