If you are serious about personal branding and not just goofing around on social media sites, you need to understand where to invest your time and effort to get the best results. I think of sites in term of their flow rate, or how often the information on the page changes or refreshes with new and valuable content. On active sites like Twitter and blogs, the information refreshes often, while on static sites like Linkedin and Facebook, the information refreshes less frequently.
I think the active sites are the best places to focus your effort because this is where people interested in your value come to exchange information and conversation regularly. You can also configure your active sites to auto-feed into your passive sites so you don't have to visit those sites as often.
Blogs (including yours) and Twitter are the places where you can really target people that have a shared and serious interest in your value platform. For example, my value platform is leadership and management, so on a daily basis I read read blogs by people interested in the same thing and try to engage some of them in conversation by leaving a comment. I also try to write my own blog posts frequently if not daily. On Twitter, I am connected to several hundred people with a either a focused or peripheral interest in leadership, and there are hundreds if not thousands more that I have yet to meet. There is no way either Linkedin or Facebook can provide most of us that number of value focused connections.
With your blog, you need to understand that once you become part of the "rain," you need to commit to contributing to the flow are a predictable pace. That needs to be a minimum of once a week, and better yet 2-4 times per week. Your community of followers needs to know they can count on your regular contribution to the flow of information and conversation.
With Twitter, you need to understand the times of day that your most trusted and valuable followers are also checking Twitter so you can be strategic about the time you spend on the site. Some of my most valued connections on Twitter are 2-3 time zones ahead of me, and they access Twitter between 6 and 8 am their time. That means if I wait until 8 am to start my Twitter activity, I've missed them. Most will be back latter in the day, but those times are less predictable.
Understanding the flow rate on my active sites, I usually write my blog post the day before I plan for it to appear. Then I post it first thing in the morning and it is the first thing I contribute to the Twitter "river" in the morning. After I toss my blog post in the river, I then go read other blogs and try to find 3-4 that interest me the most to also bring to Twitter to share with my friends. These tweets auto-post to my Facebook and are there before most of my local Facebook followers access that site during their day.
I am usually done with the most important part of my social networking for personal branding by 7 am. I'll check Twitter again around lunch and in the evening, but most of that activity is simply thanking the folks that were kind enough to retweet my posts.
"I don't have the time" is the biggest excuse you will use to not engage in personal branding. By understanding the flow rate of the most important social media sites, you can plan and budget your time wisely.