A compliment to a woman should always be honest, tactful and from the heart. A woman will be able to tell when you are being less than honest or saying things merely to flatter. Use her actual attributes and compliment her on something specific. The time and the place you choose to say these nice things to her must also be appropriate. If you thought she looked very attractive the evening before, the communal work kitchen is likely not the place to share this. Use common sense and your flattery and kind words should be well received.
A woman will always appreciate positive comments on her appearance, as long as you mean them. If it is obvious to you that she has gained a bit of weight, then it very likely is to her as well, so complimenting her physique may not be the way to go, unless her newly voluptuous body is a positive improvement. Otherwise, do not comment. If she has been frequenting the gym, trying a new hairstyle or recently tried contacts or new glasses, a comment that you noticed and like the change will be well received. She will likely appreciate a compliment on a new outfit, a particularly sexy pair of shoes or trendy piece of jewelry as well. Above all, be honest. If you are not she will know, or will find out later. Saying nothing is always better than an empty compliment.
If the girl or woman has a particularly strong work ethic and completes tasks efficiently, whether they are business or home related, relaying that you have noticed and appreciate her efforts will be well received. Tell her that you appreciate her swift and meticulous completion of the report you asked for. If she is your significant other, notice and compliment the dishes being washed and put away the night before. Acknowledgment of her efforts will go a long way to helping her feel loved and appreciated.
Compassion and Kindness
If the woman in question goes out of her way to do something especially kind or courteous, like make you dinner, give you a ride to work or help you out with your own workload, thank her and tell her how you appreciate her going out of her way to be kind. Hearing that someone has noticed her selfless efforts and has deemed her a truly good person is a reward and gift beyond most she could purchase. A well-placed compliment will go a long way to bringing some cheer to the girl's day.