Make sure that visitors to your website do not click off again straight away by ensuring that your site has a clean professional design. A professional website does not need loads of gimmicky stuff like abstract imagery, animated images or clever slogans. To ensure that you are engaging with as wide a demographic as possible, keep in mind that people from all age groups may require your services. If your site is ultra cool and trendy and appealing to perhaps a younger age group. You may find that this image will put off members of perhaps an older generation. The opposite is also true. An old fashioned website will not attract the eye of younger purchasers. Of course these statements do assume that you are selling to the majority of the buying public.
If the design of your site has a simple well coordinated colour scheme using reasonably standard fonts but not so plain to be boring. You should be able to engage with visitors to your site whether that visitor is young or old. Certainly with an online retail shop, you surely would want to be selling as many products as possible to as wide an age group as possible. An uncluttered professional design will appeal to everyone who visits your site and with that you stand the greatest chance of making many online sales.