I know what you are saying. All my life has been admiring what girls wear. It is a male trait in failing to compliment a lady on what she is wearing. Women are more free in complimenting each other so it would be a given that ,while En femme to kindly remark on what a girl is wearing. I have received many compliments on what had chosen to wear that day from friends or colleagues. It is another nice thing when a sales girl or complete stranger wanders up and compliments something I am wearing. It can lead to a nice conversation.
With regard to being at church I would assume that it is a fairly regular congregation it wouldn’t be odd to strike up a conversation about the meeting and then compliment the lady.