The common social media package that the experts recommend as of 2010 is a Twitter, a Facebook, and a Blog. I am not an expert on this topic, but I recommened a forum too, since you can generate user-generated-content more quickly on a forum, than on any other medium -- as well as generating a way to find new potential clients who find you on the forum.

Blogs are the in thing, but how to use them is not always an agreed upon fact written in stone. There are several strategies you can use for a blog.

1. Gaining a fan base. If you or the individual you hire is an entertaining writer, you can write a blog every week, or several times a week, and your people will have yet another reason to follow you in some way. Regular followers might refer their friends to see your blog, and those who don't know you that welll, will get to know you better and gain respect for you through your blog (assuming its good). Being in business is all about being in the relationships business. Social media, especially blogs is one way to make your relations more intimate and develop fan loyalty.
2. Keyword relevance. Google tracks whats in your blog. If you keep your posts rich with all of your important keywords, that will help you get better placement. It pays to link your blog posts to relevant pages on your website for link popularity.
3. Connecting your blog to your other social networks. If you merely have a blog, but no twitter, then promoting your blog will have one less avenue. You can email those assicated with your website, past customers, listings on your directory, etc., but a Twitter account is great for broadcasting links to fresh material. Twitter is all about real-time communications and information that is fresh. Each time you make a new blog post, you can tweet about it. Facebook is another place to promote your blog. However, Facebook's wall makes everything move down when a new post arrives. If you have a good discussion going, you will bury it if you add any other posts. Only post about blogs you know your Facebook fans will like, otherwise you are taking up your Facebook real estate which can cost you. I say, post links to a few blog entries you wrote on a Friday, and then post a hot discussion topic which you are confident everyone will like. That way the discussion is on top and won't get buried all weekend long.
4. Connecting all of your social networks together. Tweet about whats in your forum, tweet about whats hot on facebook, and tweet about it while the iron is hot. You can have blog entries link to relevent forum posts too. Or, you can condense your best forum discussions into one blog entry if you think that will be popular.
5. Keep track of which blog entries get clicked on and WHERE they got clicked on from. My personal story is funny. I posted about many blog topics on Twitter where our followers are not link-happy. We got 5-20 visits per topic. Then I posted about my vacation and my analytics showed that it was by far the most popular topic. What my analytics application didn't tell me was that I had posted the link on both Facebook AND Twitter, and it was the Facebook folks who found my visit to Yosemite so intruiguing. Figure out what is popular, and post more on those topics. Unfortunately, sometimes you run out of material on the really juicy stuff.
6. Commentary on blogs.The wonderful feature people always say about blogs is that you can get commentary. On our forum, we get well phrased opinions from members who know us well. On our blog, we get weak one liners which don't really communicate much of a message. Blogs are pretty much a one way street. Its not exactly social media. Its just regular online media. The advantage to a blog, is that you can post whenever you want without the help of your webmaster, and you can put all of your posts into infinite categories too.
7. Don't post too much at once.Its considered bad blog-tiquette to post more than one post per day. Two posts per week is standard. I will save up posts in my email account and post them every so often. I can write ten posts in a day and save them for months. If you post two or three in a day, then wait for a while before posting more, especially if you have a regular fan base. You don't want to overwhelm them.

Blogging is fun, and you can get wonderful benefits from it. The cost of blogging is only for your programmers to set up your system, and some systems are free. Find out on your own how much transformation blogging can create in your enterprise.