The key to this Rule is “sincerely.” You mustn’t use compliments glibly, falsely, shallowly, dishonestly, or disingenuously. Compliments must be real, honest, open, guileless and meaningful.
Being the sort of person who gives compliments is quite tricky. You don’t want to be seen as a slimeball or spooky—and people who do give compliments can often end up seen like this—but you do want to come across as genuinely warm and friendly.
So how to do this? And why? Well, if you do it affably, it makes people think incredibly well about you—it is good office karma. The best way to do it is by being unsophisticated about it. All you have to do is say, “I really like the way you’ve had your hair cut,” and then ask a question about whatever it is you are complimenting her on, and make it about how it was done. “So who did your hair?”
“I do like the way you handled that customer; how did you feel saying that?"
“I must say I liked your report; how is it going down with the board?”
Try to avoid using over-the-top expressions. You don’t love their new coat—you merely “like” it. Remember, if you “love” it, you’ll want to marry it and have its babies. Not true of a coat, or a report, or a hair style, or the way someone handles a customer.
If you “like” something, feel free to say so. You can emphasize how much you like something by
• “I really like …”
• “I do like …”
• “Can I tell you how much I liked …?”
• And it doesn’t just have to be “liked,” although it is a very good one to start with
• “I was impressed by …”
• “I thought you did really well …”
• “The way you did … was very good indeed”
• “I did enjoy your presentation. It was really rather exceptional.”
When giving compliments, make sure you can’t be accused of flirting or coming on to someone—keep it professional and/or work related. I'm sure you don't need telling this.
BEING THE SORT OF PERSON WHO GIVES COMPLIMENTS IS QUITE TRICKY.