The very simple trick for gaining confidence from your spouse, friends, colleagues, and others is to learn how to accept mistakes.
As humans we are prone to making errors in life. Sometimes the mistake could be from the work place, it could be at home or offending a friend?
When something like this happens what would you do? Would you have to concealed and put your shoulders high without doing something about it? Of course concealing your mistakes put you at a disadvantage, it does not make you to see clearly and the ego overwhelmed in you. Ego destroys a lot; it can ruin a long relationship built, destroy matrimonial homes; turn wife against husband, separate friends. And even at work place, a manager may seem to be right at all time by not accepting a little mistake made, showing autocratic management style and not considering the views and contributions of his/her employees.
By learning to accept mistakes you break the unwanted line of ego and establish a profound relationship with those around you. Considering your error may also put you at an advantage in that you've been able to acknowledged your weakness and try as much as possible to strengthen it. You learn new ways of doing things and reinvent your strategy to succeed. There are so many benefits that comes when one admit his/her fault. Mind you there are some circumstances in which you are not wrong at all, but for the sake of mutual relation and you just want peace to reign, you bury the ego and move on by not engaging in an intense argument that may bring disharmony.
Learning to accept mistake is the best skill and valuable habit one could imbibe in life. Start now to accept a simple error and move on... not until its complex, you might not have time to do so thinking that it is nothing to worry about.