First, some handkerchief history from Hudson Pocket Squares:
What is a Pocket Square?
A pocket square (handkerchief) is a thin, square, cloth used for wiping the eyes and nose. It can be made of any cloth, but is typically made of linen, cotton or silk.
The first handkerchiefs were small pieces of silk tissue used by priests and clergy at the altar. At first, handkerchiefs were carried in the hand, not the pocket. They were carried both for utilitarian purposes and for dress. They quickly became an essential accessory.
Through the ages, the handkerchief saw many uses and styles. At some point around the 18th century, the square shape was defined as being the standard, based on a version that Marie-Antoinette made. Louis XVI even published a decree stating that the length and width of a handkerchief must be equal.
It wasn't until the early 20th century that the pocket square, or pocket handkerchief, became popular. Handkerchiefs were folded and placed in the breast pocket of suits, and this quickly became the sign of style and stature. For decades, men would not be considered properly dressed without a pocket square in the breast pocket.
Since Nathaniel turned 17, he has become more interested in his appearance. Just before church recently, he asked me how to fold a handkerchief into a pocket square.
I did not know how, and we didn't have time to find out. Later that week, I looked at some pre-folded ones with matching ties at a department store, but I felt it would be a little degrading, like giving him a pre-tied necktie, so I bought him some monogrammed handkerchiefs for his pants pocket instead. Then I found this article from The Art of Manliness site that explains with written and video directions how to fold three different styles of pocket squares.
To get more ideas I visited PocketSquareZ. The site shows many more styles, but most of them struck me as too flamboyant. However, I suspect fabric choice makes more of a difference in this regard than the actual fold style. PocketSquareZ also features a few matching tie/pocket square sets.
Belisi features matching ties for every pocket square it sells. After studying them and looking at this picture from Joseph Bank,
I agreed with Art of Manliness that pocket squares should complement the tie but not be the same fabric. Plain white ones go with everything.
I saw silk pocket squares from $8 all the way to $125. The $8 one was the PocketSqauareZ silk or satin, "carefully folded and sewn together between an attractive insert card". I figure they use the bare minimum of fabric. Sewn into an insert card, they are definitely for looks only. For $16 you can get a non-folded silk pocket square from Belisi, but I could not find the measurements. The $125 one was 16" x 16" of 100% silk.
Hudson Pocket Squares makes pre-folded 100% Irish linen pocket squares in a variety of colors for $15. They use a full 16" by 16" piece of fabric, but I don't know how the fold is secured.
As far as fabric choice, a (non pre-folded) white cotton or linen is preferred if it is to be used as a handkerchief. Otherwise, keep a utilitarian handkerchief in the pants pocket and save the red silk pocket square for attracting young ladies.
One commenter on the Art of Manliness article suggested carrying two cotton handerchiefs with the silk pocket square: one for the tears of a damsel in distress, one for the man's eyes, nose, or glasses. I thought this was a good idea. After all, few women carry handkerchiefs anymore, and they cry just as much or more than ever. It gives the man an easy way to show compassion without having to say too much in what is often an awkward situation.