These accessories are usually the smallest detail men fail to acknowledge properly while dressing up, either formal or casual.
Pocket squares are the handkerchiefs that are kept inside a suit jacket pocket with their tips visible in any one of the different folds. They come in different colors and can also contrast with the suit. They should never match the tie exactly but one or more of their patterns or colors can match the tie. Silk fabric pocket squares are mainly for formal suits and its alright to try with other fabrics for casual suits.
Cuff links are much underrated/over looked and need to be given more significance. Cuff links are great classic touch to the suit that may not be noticeable individually but blend in with the outfit gracefully. They are usually either gold or silver and hence you wear them according to the color of the shirt, some cuff links also have very awesome designs. Some shirt brands come with cuff links while others don’t, this does not mean it is okay to over look them. For a finished look always remember your cuff links.
Collars have small holes in each point, allowing the insertion of decorative brooches/pins. Collar brooches can be worn with or without a tie depending on how decorative they are. Collar holes are there to be utilized, you can have a dropping double chain collar brooch or collar pins.