If you are invited to a cocktail party you will need to wear something you are comfortable standing in. It would be best to wear a cocktail dress or a costume.
For a formal dinner you may wear a long evening dress or something a bit shorter. It should, however, cover your knees. It is also considered correct to wear stockings with your dress. Again, make sure your dress is comfortable to sit down in.We recommend a flowing style, as anything too tight or restrictive will make it difficult to dance. You should choose quite, dark colours rather than bright colours.
If you go to a ball, you should choose a long evening dress, i.e. it should at least cover your knees. However, the best choice for such an event is a floor-length evening dress.
There are a lot of different kinds of evening dresses available. So best pick the style you feel most comfortable in. Before buying an evening dress, do a few dance steps and try sitting down to make sure it feels comfortable.