A waistcoat can really enhance your look in opposite directions. As a part of a 3 piece suit, it can give a very proper British gentleman look. As seen in, for instance, The Kingsman and The Thomas Crown Affair two films, you must see if you have not yet.
The other direction would be the hardcore rough late 1800 century work way that is sported by Tom Hardy in Peaky Blinders and Taboo.
A waistcoat is the perfect middle garment for a man that wants to wear a shirt when the shirt can become a bit boring. The waistcoat keeps the fully dressed look and has really useful pockets if you're lucky.
The waistcoat can be low or high and single or double-breasted just as the jacket. Just as with the lower 1 and 2 button jackets, it has been a lower cut that has been popular lately. The higher cut and with lapels have been harder to find but is now growing in popularity.
If you use your waistcoat a lot without a jacket as a self-standing garment, you should consider to have the same fabric on the back as on the front, Instead of the silk that is normally there for easier use and cool under the jacket.
Linen check waistcoat w rounded end, 3xflap pockets and narrow lapels.