Hamlets Dilemma

I feel that Hamlet is making a smart decision because he wasnts to make sure that Claudius gets what he deserves.  Claudius prays to get a clean soul, Hamlet wants him to rott in hell.  When he plans to kill him, instead of using a knife he should use poison the same way that Claudius killed his father.  People will not question a clean death, but if he is brutally murdered they will know Hamlet did it.  That will alter his future, so hopefully he plans it out and gets away with it.