To follow an artist simply select Follow this Artist. As a buyer you can then view your follows by navigating to Buyer>My Cart My Follows. Here you can see at a glance who you are following. To view their recent work navigate to the Search link and select New Work My Follows.
To make an inquiry to an artist navigate to their store and select the Make an Inquiry button. A popup box will appear, enter your note and hit send. The artist will receive notification via email and will see a notation near their name at the top of the page when logged in.
To view your messages and to reply click on the mail icon or your name at the very top right side of the page. Here you can manage all your messages.