It should be written in the rulebook of the dapper gentleman that a pocket square is a necessity for any blazer for almost all occasions. I personally choose to wear a pocket square at all times because I feel that it adds a stylish element to a blazer, and differentiates a well-dressed man from the typical sea of navy blazers you may encounter.
Pocket squares come with many price tags and the key is you don’t need to spend that much! I personally have my tailor make squares when I have shirts made from the same fabric. This way you get a perfect match to your shirt at a $25 price tag!
One of my personal favorite stores is Massimo Dutti and they often make the lining of the breast pocket on their blazers a pocket square. Hence, an easy cheat is to just pull the lining of your pocket inside out to achieve the look with minimal fuss.
If you are able however, a pocket square can take your jacket to another level of style. Here are the two rules to choosing an appropriate pocket square.
This is a Massimo Dutti example of a built in pocket square. This is a perfect spotty pocket square look for a causal linen jacket. Perfect for daytime shopping in the summer.
The daytime key is to have a triangle style square rather than the more formal straight option.
The key to a formal pocket square is to ensure it matches your shirt. Hence White shirt equals white pockets square. This provides a clean and crisp look for a formal event. You should never arrange your square into a triangle for a formal event (with the potential exception of black tie).