How to market online locally?

[horsegal]

Ok so I've posted before and got some good answers but I'm still a little unclear as I know very little about this. I've heard of various way but not quite sure how to implement them.

For example I was told social media marketing, facebook twitter etc. also yahoo answers. How do target only specific cities? Doesn't really do me any good if people not where i'm operating out of see. How does this social media marketing work?

Some people said blog commenting and article submissions. Does this work quickly and do people really read them and is this a lengthy process? How do I target local customers who have an interest in the service?

I know there are some specific sites that are related to the service I'm offering. They have forums. Is it possible to post without having someone scroll through daily and read all the post? Is there a way to automate it so that is can send a specific response and a link to the site? Can I make it so that it only comments for certain cities?

Any other ways to market locally? This is a service oriented business.