For daily maintenance stuff the money mailer thing is the best in my mind, i always go through those and see if there is anything decent in there.
For performance stuff i'd focus on google, facebook and other online things.
For the younger crowd, you could look into getting a snapchat filter for your business. Take a pic, and put yourself in a fancy supped up hotrod, something like that.
I also totally agree, since you are not hurting now, just keep doing good quality work and people will keep referring you.