Basics- Disk Space and Transfer
The core states of any kind of hosting, ecommerce or not, remain space and transfer, or traffic. Generally measured in monthly increments, your space and transfer will place a crucial role in determining just what size plan you need. Ecommerce sites will, generally speaking, require more space and transfer than an equivilant sized site without ecommerce. This is due to the presence of the shopping cart upon which the online storefront is based. Shopping cart programs are installed to the account on which they operate, requiring space, and their scripts for running the store will require additional transfer to handle customers as they browse, add items to their cart, and check out. Will there be a tremendous amount of extra transfer required by the cart? That depends on how many use the cart and on the cart itself. This is why its best to start small and having a clear upgrade path to handle future popularity.

Prospective online merchants will generally have a good idea how many products they'll be selling initially. This will vary wildly from merchant to merchant, and many merchants don't put their entire stocks online. It is wise to start with a considered selection of products first, especially if you wish to initially keep your hosting plan small and upgrade as the store prospers. Those with a great deal of products need to be aware they will probably be facing a bigger monthly fee for a larger hosting plan. Once the decision is made regarding the products, attention can be turned to finding a suitable shopping cart program to contain them.

Shopping Cart
The choice of shopping cart can be a personal one. Those entirely new to ecommerce will probably not have any experience with any kind of shopping cart software. There are a number of popular choices, and most hosting companies will provide one, if not a variety, from which you can choose. It is important to find a shopping cart that suits the individual user, as attempting to change your shopping down the road can be a long process that will, most likely, bring your store down during a transitional period. Don't immediately jump at the first cart a host offers. Ask if they have demos and try them out. Be sure it's a program you can learn and use, as it is the primary way you'll be doing your online business. Even if you have a large business and have a design firm setting up the cart, a rudimentary knowledge of the cart's processes is highly recommended.

Learn as much about your prospective shopping cart software as possible. Make sure it supports SSL, a common site security protocol that will help keep your customer's credit card numbers safe when ordering online. It will need to support your merchant account and payment gateway. In many cases a host might bundle these services, so compatibility isn't an issue. If you secured your merchant services separately from hosting, be sure they are compatible. Find out if the cart has a recommended maximum product limit and, of course, try not to exceed it. The store may slow down and perform poorly if there are too many products in it.

Finally, make sure it will do everything you want it to do. Some merchants sell services and downloadable items that don't conform exactly to the order-product-ship-product flow. If your cart doesn't support these features by default, there may be 3rd party add-ons that will provide this functionality. Miva Merchant is one such shopping cart with a very active 3rd party developer community providing a wide range of add-ons, or "modules" to extend the feature set of the original program. The merchant will have to buy these add-ons and have them installed on their own initiative, though, and the hosting company will not be able to support them.

Reliability and Support
Perhaps of greatest importance is reliability in your chosen host. Think in terms of a "brick and mortar" storefront. If someone locks the front door during business hours, then no customers can come in and nothing is sold. Similarly, if an online store is down at any hour, no customers can come in and nothing is sold. You want the most reliable hosting for such a mission-critical site. Never just take the word of a hosting company's site in regards to their uptime. Do research and look for customer reviews of your prospective host. Online merchants should always be willing to pay more for a reliable hosting company with good uptime and support. A good rule of thumb is to stay away from free or "bargain basement" hosts, since support and uptime are usually the first things to suffer with this kind of hosting.

Conclusions
Finding the right ecommerce hosting company requires a few additional considerations. Decide on your products, your shopping cart, and then shop for your hosting company. You will need more space and transfer than an equivalent site, but start small with your product selection and you can still save money on your hosting. Find a shopping cart that's easy for you to use and understand, as switching at a later date can result in downtime and a lot of work transferring your products. Finally, make sure your host has solid uptime, as an online store that's down isn't generating any sales.