Evening dresses are usually composed of long dress and gown, ranging from mid-thigh below the knee. They also vary according to the purpose of the event. There are even appropriate fabrics that will suit a party dress which are all excellent to be sued as cocktail fabrics and embellished with sequins and beading.
If you will attend a black tie affair, it will somehow require a cocktail evening dress. Pants suits or any dress suit is a no-no for a formal event unless it's a business activity. They vary from knee length to ankle. You can even choose a straight sheath to skirts and fitted bodice.
If you have a light skin tone you will want to stick with lighter colors. Dark colors such as a bright red will make you look very pale. You can also choose those that have glitter on it.
There are always new styles of evening gowns that come out. You can be one of the first to display one for your special occasion though. What may surprise you is that many of them are more affordable than you imagined. Don't assume that wearing a lovely evening gown has to be a huge expense. If you love being a trend setter then this is a fun opportunity for you do so. Don't forget to check out the various accessorized too.