If selling online, outsource the payment process, Google Checkout and PayPal are solid options. Consider "search-engine optimization," or ways to increase traffic to the site. Firms specializing in this range widely in quality and cost, but you may be able to achieve some results on your own; checkout SEOBook.com or Hubspot.com for tips.
Create Facebook, Twitter, etc. accounts for the school so you may keep students updated on school events or alerts, such as closing due to weather. Make regular updates so students will get in the habit of checking the sites regularly.