I post to lots of other groups. Here you can also post blurbs and/or extracts. I am not sure how useful it is. There are so many others doing the same thing. Local newspapers are useful if you can get them to put something in about you. Anyone who contacts me via my website I put in my contact list and send out a bulletin when anything is happening. If you can give a talk to a group it does mean you might sell some books, always make sure you have some books with you to sell!
It is very difficult these days to promote yourself but you have to keep at it...no good being a shrinking violet these days, although that would, I confess, be my preferred option.