This week we have two ballroom tips, to make up for my inability to post last week. After discussing the characteristics of ladies' competition shoes, it is clear that there are dozens of options available. Heel height and strap style depend on the shape of the foot, and a dancer should try on shoes until she finds a combination that works for her feet. I can't give any guidance there. About shoe color, however, I can offer a few general guidelines.
The first question to ask yourself is, do I care if people look at my feet? If the answer is "No," feel free to select the pair of shoes that look gorgeous in a color you love and have fun with them. This option is not available to competitive dancers. If you are registering for competitions, you must care about your feet. You are paying for judges to evaluate your footwork, and so need your footwear to present your feet as nicely as possible.
For most dancers, "as nicely as possible" means "inoffensively." You don't want to attract attention to your feet. You do want to have the longest leg-line possible. This is why tan and nude shoes are the universal footwear of competitive ladies. They blend in with the leg, more or less, and they blend in with the floor to make your legs look long and your footwork look inconspicuous. In the dance world, tan shoes go with everything.
Black shoes do not. Wearing black shoes will visually break your leg-line, making you look short and making your feet look big. You don't want this. The only exception to this is if you are wearing black fishnets and a dress that looks good with black fishnets (this, for example). Then tan shoes would break the appearance of your leg-line, and black shoes make sense. This is also why men's shoes are almost universally black--they wear black pants all the time.
These things being said, there is a long tradition of wearing shoes that call attention to your feet, because the dancer is confident in her footwork, wants to call attention as much as possible, and is willing to acquire shoes matched to specific costumes (latin examples, ballroom examples). Stoning shoes is common, and there is a long tradition of dying shoes to match costumes, particularly among standard dancers. Personally, my footwork isn't that great, and shoes are expensive enough that buying pairs for specific costumes doesn't make sense. I stick with tan.