have a good head on (one's) shoulders
To be capable of making sound, responsible decisions. Joe has a good head on his shoulders, so I highly doubt that he would go to Vegas and gamble all his money away.
good head on one's shoulders, have a
Be intelligent or shrewd; have good sense or good judgment. For example, We can depend on George to figure it out-he has a good head on his shoulders. This term originated in the 1500s as have an old head on young shoulders, alluding to the wisdom of age and physical youth. It took its present form in the 1800s.