Rule: Feed your fans.
"Many of us paint on the street so our work can be see by more people, but you should never stop there. 1000x more people will see your work online.
Think about how many artists' work you know and love, but you've never seen their work in person. The web can be a great way for people to find your work, but then you have to find a way for them to keep coming back to you.
Just because someone loves your work doesn't mean they are going to follow everything you do. You have to let them know what you are up to, either by social media or a mailing list. It may take years to build a good base of followers, but each time you meet someone who likes your work or sell someone an artwork, you should keep in contact with them in some form. It might be someone you met five years ago for a second that has followed you and all of a sudden needs a huge wall painted or wants you to exhibit in their new gallery."