If you have lots of extra time on our hands and want to play with social media for fun, that's fine. But, for most professional artists who are running a business, time is a very valuable resource. So, it is important to know how to utilize the media in the most effective way.
Your goal, first and foremost, is the create GREAT CONTENT. You can do all kinds of things to get people to your site. If you don't retain those prospects, you have gained nothing and have lost a lot of time and effort. You need to change your focus. Use the media to promote a project that has a way to either make a sale, retain a prospect for future sales or both. Ultimately You are BUILDING COMMUNITY. This community building ideology is also important/valuable when pitching projects to publishers, film, merchanding etc. If you establish a strong community/fan base, you have something marketers want to be a part of.
Website: Determine what your site will provide for prospective markets and communities.
Create the site to be engaging enough to sustain an ongoing interest from your target audience.
Design the interactivity to be easy to access from a multitude of devices.
Think ahead and allow the design to be flexible for adding, updating and changing as time goes on.
Use a Statcounter or Google Analytics to track pages and visitors. Use Google Alerts to track content mentions on other sites.
E-commerce aspects for direct purchases can use Paypal or credit cards using secure access like Verisign.
Affliate programs are also a way to make money through your site.
Dick Blick Affliate
Partnering with Etsy, Fine Art America, Zazzle, Cafe Press and other such vendors can make purchasing and even order fulfillment easier.
YouTube: Develop your own channel and monetize your videos. Promote your products and other content using video that can be easily created using imovie or moviemaker.
Periscope Live videos to an audience.
Videos are great promotional initiatives to place on all your social media!
Use social media to distribute your promotional initiative. Facebook can show links with icons and direct video access. Join all the appropriate groups and post your links, video, etc. to these groups. This will distribute your news out to the masses.
Twitter can be linked to Facebook, so that each time you post to FB you are tweeting. Adding appropriate #s to you FB posts will further distribute your message.
Linked-in also has groups to join where you can post promotional content to.
Behance and Instagram are also great ways to share content.