1. Facebook: This name comes in mind first, at least to me, because letter F comes first at No. 6 among English Alphabets. Also, this is most popular. You, me and people like us made Mark Zuckerberg so successful. Perhaps, in your Facebook, you already have loads of friends. Organize your Facebook profile so people know your skills in much better ways. May be some may help you in getting an Interview call.
2. Twitter: A beautiful, microblogging platform loved by Entrepreneurs and skilled professionals. Unlike Facebook where sending friends request to unknown friends is a sin, on Twitter you can follow any Tweeter and get follow backs and comments.. Chances are you will meet some masters inside Twitter. While working for Zeddes.com, I met Lolly Daskal, a Social Media influencer inside Twitter. She is master of the game. If I can, so you can.
3. LinkedIn: Great to get recommendations. Join LinkedIn, follow everyone from your Email list. Remember, more people will bring more people your way. LinkedIn is full of job seekers like you, HR managers and Entrepreneurs. Optimize your LinkedIn profile for maximum performance. An Interview Call may come your way. I love reading 40billion.com via LinkedIn
Efforts pays the dividend. When I was planning job change very first time, some 10 years back, what I did is taken 3 days leave, sat in a Cyber Cafe and applied for every company suitable with my profile. In those days, I was not having Internet at home. In the of 3 days, I felt, may be I did a wrong thing, Cafe was costly too, and I didn't get any call, money wasted. Luckily my profile was optimized for better performance and I received an Interview Call from a gentleman (CEO of a company). He was searching for the likes of me, and you can understand, this was my day.
4. Reddit: This good old platform is great for discussion. You can find many topics and subtopics inside. Really superb at least in my knowledge to exchange ideas and learn new things. My Reddit is HERE
5. Google Plus: G+ is great to meet really really knowledgeable people, academicians and experts. I met many inside. G+ comes at No. 2 after Facebook. May be you can meet your next employer or find a next best friend.
Precaution: Learn time management well, spend time on Social Media wisely. You do not need to be there 50 times a day. Concentrate on learning new things and polishing old skills, share your stories and creations inside social media within permissible time limit. Do not get lost inside.
"Where have we lot knowledge in information, where have we lost wisdom in information"- John Keats