The first thing to keep in mind while searching online is to consider the place that is selling the shoes. You want to make sure that it is trustworthy. There are many shops online that have unscrupulous business practices when it comes to footwear. Such places sometimes pass off couterfeit products as authentic, sell used shoes instead of new, or sometimes do not even ship the correct pair. That is why it is so important to do a bit of research on the vendor you end up purchasing from to make sure that similar issues do not happen to your order. I generally reccomend purchasing from major retailers such as Amazon so you know that you can trust them to ship a quality product that is authentic and legitimate.
The second thing you may want to consider when shopping for stilettos online is the risk that auction sites such as eBay pose. This goes hand in hand with the above considerations in that many times on eBay the seller may not have your best interests in mind. There are thousands of cases every year where the buyers end up getting items that are significantly not as described and it ruins their experiences as well as costs them the money they paid. If you choose to use an auction site such as eBay to purchase your pair of black stiletto pumps then it would be in your best interest to research the seller and make sure that they have good reviews. Also look through their feedback and make sure to read about any bad experiences past customers have had. If the good drastically out-weighs the bad feedback then make sure you take any bad feedback with a grain of salt in your considerations.
The last thing that you should really keep in mind when purchasing any shoes online is your budget. It is very easy to completely forget about a budget when shopping online because nearly any brand and style of stilettos are readily available for purchase. But just because they are available does not mean that you have to go all out and put yourself into financial trouble. You set a budget for yourself and then make it your goal to search all over to try and find the best match that fits what you are able to spend. A good tool for staying in your budget and getting the best deal is to make use of comparison shopping sites and large trusted marketplaces like Amazon.com. Often times because the competition is so stiff from other companies looking for your business, you can usually find a sexy pair of black stiletto pumps that are discounted or on sale.