THINK BEFORE ACTING!!

Rashi says in two places [Makkos 10a and 10b] that a רוצח בשגגה is a רשע. 

The Torah says that one who kills בשגגה is בבלי דעת - w/o thinking [דברים י"ט ד]. 

From we see that one can even be a רשע  when acting w/o thinking.