I have always believed that giving and receiving constructive criticism is an art form. The constructive element must be the driving force that allows the comments to be made. Too often, the comments start out as criticism, and then are merely “sugar coated” to try to convince the recipient that the intent was to benefit them.
It is also important when giving constructive criticism, to understand how the recipient may interpret your intentions. Since the constructive criticism is for the recipient, it may need to be tailored specifically for the recipient.
If the recipient is fiercely independent, and believes that any suggestion of change implies that they have failed, their first reaction to any suggestion or constructive criticism might be very defensive. With this recipient, it is usually better to open up a discussion on the topic that may need to be addressed, and attempt to steer them into seeing how the concern should be addressed. Take advantage of the power of their desire for ownership, and the change that you are seeking will be their idea.
This solution will require more time and diplomacy. If done correctly, and with patience, there should be no need for the recipient to become defensive, and you won’t need to try to ease their anger with a line like “I was just trying to give you some constructive criticism.”