Reliability
Most sites will make promises of 99% and more guaranteed uptime. In reality these guaranteed are pretty difficult to enforce. Instead you will need to rely on the reputation of the company or your own personal experience.

look for features like load balancing which ensures that the data stored on a server is is quickly accessible, even at the busiest times of the day. Identical copies of the site are hosted on more than one server. If the load on one server is too great, visitors are redirected to another server which is not so busy.

Location
Usually you should choose a web host which is located in the same country as yourself. It not only make telephone support easier but search engines sometimes use the location of a server as a means of helping decide which national directory to place a site in.

Disk Space
Try and estimate how much space your site will take up. Most new web sites need a surprisingly small amount of space, sometimes less than a megabyte. Even the most modest of hosting packages should be able to supply this. Unless you site is heavily dependent on graphics or has masses of pre-written content, you are unlikely to require more.

Tech Support
Look for a host that has 24 hour support every day of the year. You site should be open for business and able to accept orders 24 hours, 7 days a week. The majority of the larger hosting companies are able to offer this as standard. Telephone support is essential. If your web host offers email support only, it may mean you have to wait several hours before you can get a reply.

Perl Scripts
All paid accounts should offer the ability to run Perl CGI facilities as standard. Use only hosts which allow you to install your own Perl scripts and not just ones supplied by the hosting company. They will offer the ability to host a wider range of shopping carts on your own site, including the advanced Perl version of our own software.

SSL Secure Server
Merchants who are not using not using a third part credit card processor and are collecting the credit cards directly via their own own website will require a secure SSL facility. Your customers will expect to see the secure padlock symbol at the bottom of the browser screen and will be reluctant to make an order without it.
Note however that some payment processing companies such as Worldpay or Authorize Net provide their own secure server for you to use. This means you will not need to purchase another one from your web host.