I'll put my "IT cap" on for this reply...
We need to clear up several things - notably about security and threats an such like through social media, etc.
Firstly we need to look at passwords. Any password that is based on sensible word from a dictionary is a bad thing to have. Particularly if you are not changing O's for 0's etc. The best passwords are random collections of letters and numbers that make no sense at all. Obviously this means they are hard to remember, but hey, you cant have everything.
Secondly we need to understand that using the same password, particularly if it is simple, is probably even worse than the above.
Thirdly I will assume that, particularly us gentlemen wont resort to using our "maiden" names for passwords either... Likewise don't use anything that can be easily determined - like street name or house number or daughters name or whatever.
I know passwords are hard to remember, so if it's really a problem go hunting for a password manager.
Next thing - can I assume we all have good anti-virus scanners? Anything is better than nothing. I'm not going to try to tell you what's best, but I do use AVG free on my home machines - it works for me. 'nough said...
So having said all of that let's look at social media...
Firstly and most easily dealt with is Skype. Having created a Skype account and put in place a strong password, all you will find by default is the testing user account that lets you make sure Skype is working. Note this next bit, because it's important - the only way to connect to people, or find people you know is by searching for them. The ease with which you can find people is based on the information they have made available in the Skype "directory" (for want of a better word) and this is the same for you. So if you don't want to be easily found don't put much information in. Rely on email or some other means to communicate your Skype ID to people you want to talk to. Even then you must request to connect to someone else - someone wanting to connect to you must get your permission to do so. So if you have no idea who someone is who is requesting permission to connect - DENY it! And if they pop out of the wood-work later as someone you know then it can be done again. Yes you can receive file transferred over Skype - but your AV scanner protects you from any threats there. I'm not aware of Skype being an attack vector for malware or anything else - Google is your friend for checking on this.
Twitter is a micro-blogging site and all our athletes are currently using or abusing it. Do I use it - Yes. What do I use it for - Mostly I follow other people, I don't tweet much. Who do I "follow" - Some Kiwi comedian's, the NZ AA, Topgear and associated people, lots of IT people along with @NewZealand and @Sweden and some other people whose names escape me right now. And HobbyKing. Why - because it's interesting and it allows me to interact with people who I would not interact with otherwise, and I get value from it. Do I consider it a threat or security risk in anyway - No - as long I don't tell people that I'm going away for a holiday for 10 days and my home address is blah blah blah.
Facebook. Ahh yes - the elephant in the room, the site where the rules change almost daily it seems and much may or may not happen. This is the hardest one to deal with. Suffice it to say that as long as you set the permissions about who can view what you post you are minimising the risks. Do I have a Facebook account - yes. Do I use it often - no, barely monthly. Note however that once again, Facebook has the "I-want-to-connect-with-you,-OK-I'll-let-you" paradigm in place. You don't have to connect with people you don't know or don't know well.
You can be safe online as long as you understand the implications of what you are doing.
Don't share ANY information you wouldn't want to become public (like you address, phone numbers, email addresses, holiday dates, etc)
Don't allow connections from or connect to anyone you are not sure about.
If you are not sure - don't do it.
There are risks involved with using social media, but as most people on THIS site are consenting, informed and mature adult's, I would expect that we would all be able to evaluate the risks and navigate the pitfalls without too many problem. Or ask, as has sort of happened in this thread.
Quite frankly I consider purchasing stuff online to be a greater risk than most social media. Umm - I take it that we would never, ever give our credit card information out on a URL that is not starting HTTPS, right?
Hopefully this helps a little. I've chosen to ignore the stuff about not liking various social media services - that's another "religious" discussion best avoided...