1. THERE ISN'T A SINGLE ANSWER TO THIS QUESTION -- there are many different ways of doing it -- but you have to choose some kind of answer. The worst thing to do is just to let things happen because then it is usually bad things that happen. Worse still, things can happen and you are not even aware of it because something you say to one person puts off someone else and they never mention it.
3. IF YOU MIX WORK AND LEISURE BE VERY CAREFUL. Another choice is to use the same account on Facebook, Google+ or whatever for both your work contacts and your friends. This saves a lot of time but the you need to be very careful what you say. It's probably a good idea to never say anything bad about your boss and colleagues anyway, in case someone leaks it -- maybe one of your trusted friends is not so trustworthy and shares your secrets with all the wrong people. You should also consider carefully what other things you post in a mixed network because it can get you into trouble one day. People have lost their jobs for being negative about their customers, their company's products and, of course, the boss. Maybe when you were hired you signed a Social Media Policy. Quite likely it lays down the rules for this so make sure you know what you signed.
4. AVOIDING ALL PERSONAL CONTENT MAKES YOU LOOK ONE DIMENSIONAL. If you are using a network purely for work it is a good idea to occasionally let a little of your personal life appear because this makes you look more human and easier to communicate with. Some mention of your personal interests can help break ice when you talk to people but avoid topics like politics, sport and religion that can alienate people. Remember that every time you mention politics it is likely that you are turning off about half your work contacts. There's no need to keep your politics secret but you also don't need to push them in people's faces.
5. CULTURAL FACTORS CAN BE IMPORTANT. When you work in a global community remember that there may be different views on networking activity in other cultures. Some are fairly obvious, like avoiding sensitive topics when sharing with people from strongly conservative cultures. Perhaps less obvious is that the distinction between work friends and friend friends is clear in some cultures and more fuzzy in others. In the US and other countries you can easily keep people in compartments but in those cultures that Fons Trompenaars calls "diffuse" you might find that this distinction is not understood in the same way and sorting people into categories can cause offense. Another non-obvious culture issue is that taboo subjects are not the same everywhere. In some countries you should avoid talking politics, in some you should never ask what someone earns and in another you should avoid talking sports. If in doubt ask someone for help!
Exactly how you keep your private and work life separate or mixed depends a lot on your circumstances, culture factors and your personal goals. There are many more things to consider and if you have any specific questions you are welcome to put them in the comments. But whatever you decide it's important to decide something and be in control of the way you appear.
Related Posts on Networking:
How to Separate Work and Private Networking
Involuntary Networking: Why First Street is Fascinating but Scary
LinkedIn Etiquette: How to Approach People You Don't Know
Selling Your Ideas: Influencing Your Way to Success
Professional Networking: Five Sites You Should be Using
How to Use Twitter for Professional Networking
Sign Up Now: Joining New Networking Sites Boosts Your Reputation
Zerply: Three Thumbs Up, Two Thumbs Sideways
Three Keys to Networking
Lectures, Workshops, Coaching, Writing about Networking
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