It is important to have a virtual shopping basket or ‘cart’ viewable at all times so users feel like they have it ‘with them’ whilst they are browsing your site, and it also keeps them aware of what’s in there and that they can add or remove items at will, just as in real life.
The Amazon shopping basket is great example:
The blue colour makes it stand out perfectly and its slim design makes in non-obtrusive. The details are kept brief and important showing quantities, prices and a product title which when clicked upon takes you to the product you’re buying - a nice touch. A very important feature is the ‘edit shopping basket’ button which is nice and clear and assures the user that they can always add or remove items nice and easily.
The two ‘Proceed to Chekout’ buttons are also very prominent here and are located near the shopping basket because it’s likely that you’d want to check what’s in your basket before checking out.
One final point I’d like to make about shopping baskets is to keep the name consistent. Don’t go switching between cart, basket or trolley at will as it could confuse less experienced users. The basket is there to reassure and to be convenient to users, following these guidelines and taking a page out of Amazon’s book will help you on your way.