Read reviews to find out how the lingerie your looking at fits. Some run small, some run large. When you look at lingerie, don't expect it to look the same on you as on the model unless you are about the models size. If you are in between cup sizes, then choose the smaller size that will fit for lingerie, as support is important. If buying a teddy with a thong bottom...smaller is NOT better. For corsets- get the best you can- these are tight and will not hold up if not constructed properly. You want steel boning and sturdy construction. This is the only lingerie item that quality really does count unless you plan on wearing it only once or twice. Check on return policy before ordering online and if they do not post a fit chart- ask for one before you order. A small of one brand is a medium in another and an extra small in yet another brand- and nothing worse than getting lingerie for a planned evening, only to find it does not fit and you won't get the correct size back in time.