Observe to see what prompts the barking like sounds, passersby, being alone.
Identify Triggers
Use positive reinforcement to teach "quiet" and "speak" commands. Always reward silence.
Training
Make sure your dog gets adequate walks and playtime to prevent boredom barking.
More Exercise
Limit access to windows/doors to control alert barking. Close curtains/blinds.
Manage Triggers
As a last resort, citronella or ultrasonic bark collars may help curb excessive barking.
Anti-Bark Collars
Excessive barking can indicate anxiety. Try calming aids, pheromones or training.
Check for Stress
Don't reward demanding behavior with attention, or the barking will continue.
Ignore Attention Barking