If you expect accountability from your employees, as any leader should, you need to set the tone by holding yourself accountable.
Set high standards and always be honest, especially if you come up short.
Accountability starts with you. Hold yourself accountable and you will show others what you expect of them. Aim high. Be a role model and take ownership for your actions. Don't be afraid of trying and falling short.
Nurture accountability by rewarding others for honesty and integrity.
Accountability can cascade through your organization. In addition to setting the tone through holding yourself accountable. Encourage others to take ownership for their actions including acting with integrity and honesty.