One of the benefits of the popularity of social networks is that we can build a personal brand and reach a broad audience. We can open our target market up to the world and are not limited to our city, state, or country. It is tempting (and common) to have a presence on several platforms rather than restrict our reach. Yes, there is overlap, but why not reach as far as possible when these sites are free to use.
A Consistent Voice
The challenge with all of these social networking sites is that we need to have the same message and presentation of our brand on all of them. This hurdle is only made more difficult but us adding a site here and a profile there. If we sat done and created all of our profiles in one sitting, whether a few hours or a few days, then it would be routine to make them all very similar. This approach is not likely when we add a profile now, then one in a few months, a couple more next year, and so on.
That being said, we can build a list of our profiles. Then we can do a review of them all in one sitting or short period. In fact, this profile review and update should be performed on a regular basis. I recommend at least once or twice a year.
Start With a Strong Message
Whether starting out or doing a review, your first step is to define and refine your message, image, and thus, your brand. The voice, attitude, images, style, and flow should all speak to your brand. If you struggle with this, then check out a book or post on how to define a brand. People far more talented than me have provided a lot of content on that.
Once you have that core message and look-and-feel defined, then you can proceed to adjust every profile to match that brand. Be aware that some tweaks may be required depending on the platform. There are general platforms like a Twitter or Facebook. However, the niche community sites are far more prevalent. This includes platforms like LinkedIn and many corporate community sites. You should also be clear on acceptable use both stated and implied. When you join a website and start posting, your goal is to be true to your brand. However, do not do so in a way that may offend the community. A mistake like that can cost you more than your audience on that site.