These are 2 pieces of info about SEO and Content Marketing (like blogging). It says start-ups but for beginners (or people just getting started in this stuff like social media and SEO), then this will be helpful to you too.
This morning someone asked me about social media. You have to be where your prospects and customers are. SO ASK THEM! If none of your customers are on twitter, you can probably let that go. If you are B2B, Facebook will just be an additional place to have an online page just for Branding purposes. (That is way different from Lead Generation.)
The best Google juice comes from current, consistent, relevant content, which is what Content Marketing is. For many, that equates to blogging, but it can mean other things, like slideshare.net, LinkedIn (Answers, blogs, groups), a forum, YouTube, iTunes, or any number of other places that you can curate content.
Right now, 2Q2012, G+ is being given extra credit for G Juice, so you might want to consider that as well. In addition, right now, twitter and Facebook are not indexed by Google, so you won't get any extra juice for those sites. Only LinkedIn company pages and profiles get indexed. However, if your audience is on LinkedIn, there are ways to be active there effectively.
Here is a slide deck on Content Marketing.
Here is a 10 minute video about SEO for Beginners.
If you need help with the strategy for online marketing, that is what I do, like an outsourced CMO or in a lesser role a project manager for your marketing, interacting with your website team, PR firm, inside marketing folks and your social contractors.
BTW, most of the G Juice and SEO is wrapped around the key word (or key phrase) that you are trying to rank for. Know what key word is relevant for you!