Before you can really appreciate what eCommerce can do for a business, you need to put yourself in the customers shoes.

"If I was my own customer, what would entice me to buy from this store?"

Customers like websites to be easy to use and they need to trust you.
Intuitive navigation is important. Getting your customers to the products they are looking for needs to be simple.

Once there, you want to see everything you are likely to want to know. Specifications, dimensions, colours, photos etc are all key deciding factors when comparing goods online.
Not forgetting, of course, that a clear price structure is VERY important. You need to be able to work out how much a product is going to cost you without needing to reach for a calculator or navigate away from the page you are on.
Prices need to be clear and upfront, no compromises

Shipping and Handling (or postage and packing or delivery or whatever you choose to call it!) are another big deciding factor when buying online.
Clear, simple shipping charges always work best and, as a customer, if you see a complicated shipping chart or, worse still, don't see one at all, you will head elsewhere.
Keep your UK shipping down to a few simple price brackets if possible and enable clear navigation to your shipping charges and your customers will NEVER be deterred by not being clear about how much they need to pay.

An upfront website with no hidden costs will instil trust into your customers and ensure that they are guided safely through the online shopping experience in your store