Immediate Honesty

Give feedback ASAP. The longer the delay, the further away they are from the state of mind in question. You create stronger, more appropriate associations when you provide live feedback.

Email is slow feedback. It's harder to guarantee that your recipient is in a desired state of mind to receive your message.

Even in a live situation, it's hard to get someone into an open enough state to receive. I make them feel loved before I say anything, even if its a compliment. (Compliments can easily be misinterpreted as flattery.)