I always wear a white pocket square or handkerchief. Like so:


I find it is a classic look that goes well in any jacket, with any outfit. Of course this thread may change my habits, I have many hankies in fact there are two on my desk right now. Another thing to think about I normally carry at least two with me in addition to the square in my breast pocket, one for me to use and one for a lady, I routinely give one away.