When you are choosing the type of evening dresses to buy, you will need to think about the event that you have coming up. The problem is that the different styles will work for different events. For example, shorter dresses work for birthday parties while dinner parties will usually call for long evening gowns.
Take your time to talk to other guests who are attending so you can find out what they will be wearing. This way you will all match so you will not stand out for the wrong reasons. The invitation will also give a lot away to help you determine the type of evening dresses that you will need. An invitation that says "black tie" will mean ankle or floor length dresses while one that says "lounge suits" will require the shorter, cocktail style; this is a great way to determine your needs when you really are in doubt and do not want to telephone the event organizer for more details.