The British Airways Avios shopping website can be found here.
One way to maximise your Avios points is to spend through the BA Avios eStore website.
You can collect a good amount of Avios through this method, and the range of linked retailers means there is always a good chance you can earn additional Avios through your regular spending.
The BA Avios eStore can be accessed here, and you will need to log in to your British Airways Executive Club account to view the different offers which are available.
If you search for the retailer which you are looking to purchase from and select it to shop from it. Once you have selected the Shop Now button, you will be taken to the retailer via a tracked link, which will enable the Avios to be earned.
Under each retailers logo, you will see the Avios earned, per pound spent.
Clearly, this method is best used when you are planning to spend at the store in question anyway, regardless of the opportunity to earn Avios. But it can be an incredibly good way of boosting your Avios earning potential, to always check the BA eStore prior to purchasing any items.