By far the single biggest look changer comparable to size and actual use. This extra of a mans outfit has been poking its head over the edge for centuries either as a sort of plumage in our welted breast pocket or stuffed up the cuff to show at court.
It seems Richard II King of England may have invented the handkerchief as early as the 14th century. It is recorded that he did use squares of cloth to wipe his face and nose with.
The handkerchief while very popular during the 17th to 20th century had lost appeal in the last few decades due to the pocket tissue being so handy and cheap to buy. But over the last few years a surge has been seen and wonderfully the hanky is back in action.
Handkerchiefs come in cotton, cotton blend, silk and linen. The variations of colours and patterns can be truly wonderful but those are normally silk as it takes to print much better then the other materials.
Being bold with your hanky is the one reason to have them. Having some flourish and flair in your outfit. This can be either will a delicate pocket square or something altogether more fanciful and fun.
Below are 3 pictures of good uses of a handkerchief in more casual outfits borrowed from a great fashion chap named Guiseppe Timore on his Blog 'An Affordable Wardrobe'.
The above is a contrast use which works well. There is a insignia on the handkerchief that seems to match the tie one but colour wise it is a contracts rather than a matching fabric so you may need to play around and see which work best with what tie, shirt combo.
The above pale gold hanky seems to pull out the yellow pin dot in the tie very well and also contrast brightly against the navy jacket.
Here again a yellow is used. All three are silk, you can tell by the way it folds and holds it shape. This yellow works as it picks up the yellow in the jacket mostly. Great things about tweeds is that they will have quite a few shades and colours for you to play around with.