Choosing a tuxedo shirt depends on the look you're trying to achieve. They can either go unnoticed under a vest, or can be any semi-transparent poly-cotton blend that comes with a tuxedo rental. There are also other options that you can choose from:

Tuxedo shirt collars
Like dress shirts, tuxedo shirts come with different collars. The most popular collars include the wing collar, lay down collar (aka regular collar) or mandarin collar. Spread collars are also available. The most modern of looks is the lay down collar. That said, the most traditional is a wing collar coupled with bowtie. To each his own.

Shirt pleats
You may believe that it's the frilly pleats on the front of the shirt that distinguishes a tuxedo shirt from a regular dress shirt. Think again. While pleats are an indication that the shirt you hold is indeed a tuxedo shirt, many tuxedo shirts come with flat fronts, which provides for a crisp 007 look. Pair a plain white tuxedo shirt with lay down collar, with black long tie and slim fit tux and you've got a tuxedo that's in style (right now). Think of a GQ advertisement for a Hugo Boss Tux. In sum, there are no rules as to whether your tuxedo shirt needs to have ruffles or pleats. You make the call.

Cuffs
A tuxedo shirt should come with French cuffs, and should be worn that way. Keep the barrel cuffs that you normally wear for a day that's not quite so formal. Most tuxedo rental packages come with a shirt that can be worn with or without the shirt studs and French cuffs (and cufflinks). Forget that idea. If you never wear cufflinks, here's your chance.

Tuxedo shirt studs or buttons
A typical tuxedo shirt is distinguished from a regular dress shirt by its shirt buttons. They may, in fact, be non-existent. This is because you are supposed to provide your own shirt studs or buttons, be they mother of pearl or silver with black onyx inlay. These buttons may extend down the front of your shirt, depending on the price point of the tuxedo shirt that you purchased. A tuxedo shirt that comes with a rental package will only have a few buttons, with the idea that you are either wearing a tuxedo vest or cummerbund.

Switch into your own shirt
This raises the idea that you may be able to switch out the polyester-cotton blend tuxedo shirt that comes with the rental tuxedo for your own white dress shirt, so long as it's not a button down shirt. Wearing a button down shirt would be absolutely hideous and everyone will laugh at you (inside their heads or in your face!). That said, if you're wearing a vest and long tie, your long tie will cover the shirt studs (which aren't there, because you're wearing a normal dress shirt) and the vest will cover the mid-section of the shirt wear other shirt buttons would show. No one will be the wiser, and you'll be able to wear something familiar.

via GG