LinkedIn is essential for a successful job search today. At a minimum, you need to have a complete ("All Star") Profile. If possible, you need to be active in the appropriate LinkedIn Groups for your work and location, sharing information and making solid comments.
I strongly recommend that -- if at all possible (and sometimes it is not possible) -- people continue working in their old jobs while looking for their new jobs. If you have the option to stay employed, you are much more attractive to an employer when you are still employed. Not logical, but very human (here's why).
Once you have a new job, don't drop LinkedIn. It may well help you be more successful in your work. But, best of all, your next job might find you on LinkedIn, unless it is obvious that you have dropped out and aren't paying attention.
Some employers look for a dramatic increase in your LinkedIn activities as a sign that you are job hunting.
Which can lead to job loss. So don't ramp up your LinkedIn activities too dramatically.
But, most people in LinkedIn are working on expanding their network, sharing good information about their employer's products and/or services and learning from industry thought leaders.
People also use LinkedIn to get in touch former colleagues and old friends and to meet new potential clients, all to help them improve their job performance.
So, being in LinkedIn can also mean you are a savvy business person, leveraging current technology to improve your ability to do your existing job better, through better networking, and learning new skills.
NOTE: Some employers do not want their employees using social media, particularly during working hours and/or using the employer's computers, networks, etc. Check for a "Social Media Use" policy (and also an "Email and Internet Use" policy), to be sure that you are in compliance.
Check to see if others in your group, particularly managers, are using LinkedIn, and observe how they are doing it before you jump in. And, if asked, explain that you are expanding your network so you can do your job better, just like they are.
If you are employed, don't make it obvious that you are job hunting!
However, if no one else is in LinkedIn, don't take that as a sign that you have free rein to do anything you want! Someone from your current employer could join, and expect to "connect" with you. I've even heard of clueless recruiters checking out a potential job candidate by contacting the employer via LinkedIn. So do be active, but also be very careful!
[MORE: Stealth Job Search Networking .]
LinkedIn is a big help for your career, your employer, and – when you are ready – your job search. Participate regularly, and it will pay off for you. And don't quit using LinkedIn when you have landed your new job! Keep your Profile ready for that next job search, unless your new job finds you first (on LinkedIn).
Online job search expert Susan P. Joyce has been observing the online job search world and teaching online job search skills since 1995. A veteran of the United States Marine Corps and a recent Visiting Scholar at the MIT Sloan School of Management, Susan is a two-time layoff “graduate” who has worked in human resources at Harvard University and in a compensation consulting firm. Since 1998, Susan has been editor and publisher of Job-Hunt.org. Follow Susan on Twitter at @jobhuntorg and on Facebook, LinkedIn, and Google+.