Most business professionals treat Linkedin as a virtual resume instead of a connecting tool. There are even features that allow you to print your profile in order to literally use it as a resume. What are you actually saying on your profile may not be the self you're trying to convey.
Linkedin has been around long enough and is the standard for business networking/development in this decade. Having an incomplete profile just shows you don't care. It's free, why else wouldn't you have spent some time working on your presence on Linkedin?
Even if you don't spend much time on the site, spend the time required to accurately convey who you are and who you'd like to welcome interaction from.
In order of appearance on your Linkedin Profile:
Your About Me Snapshot
They say 90% of communication is non verbal, being that Linkedin is online we'll go with 100% instead. Your picture says a lot about who you are (1,000 words worth?). Did you care enough to have a professional headshot taken? Is it appropriate for your line of business? Would you hire yourself or wonder would you rather grab a beer with the person in that photo?
The entire first section (or About Me) is where the majority of the information people will use to form an opinion on how you and your business has been doing. What are they doing now? Is there a recent status update or article? How many connections do they have? Can I find their website? Does their website still say “Company Website”?
Your summary can highlight some of your skills and accomplishments, but why list them like you would on a resume? I would say the majority of profiles I have seen (are you guilty too) are dry, boring, and so full of industry buzz words that a laymen may not have a clue what you just said. This isn't the place to show case your ability to use acronyms or to explain your proficiency in completing TPS reports.
This portion is so high on your profile that it makes it important. Show a little intelligence and some personality and tell your business partners a little about what you're working on.
Obviously, where you've worked and for how long is going to tell a story about you. If you've moved around or been doing some consulting, find a way to highlight that. Try not to itemize all of your job responsibility for each employer but be sure to include what you specialized in and a little about the firm.
Try to highlight all the positives you can, people will see a common theme in all of your work if it's consistent, even if there are a number of different types of employers.
Please don't list your civic contributions on your Linkedin profile as your employment. The true philanthropic don't care about the recognition. If you are the president of an organization than maybe (depending on the time that is required to devote to your organization). No one cares if you were the secretary for the bowling league for your BNI group.
To show that you actually are a professional, you should really have a few recommendations. They may not come automatically so don’t be afraid to ask for them. They are important though. Some even go so far as to purge some to keep them current.
Just have a few at least!
To show that you are a professional who has an interest in your own development, you need to belong to a few trade organizations that are relevant for your career. This is also where you can show your involvement in civic activities by showing that you're active in your Rotary, Chamber of Commerce, or even if it's just your old high schools networking group.
In closing, just be aware of what your profiles actually says about you. This was pretty high level post that was meant to help stir a little thought. Be aware of the information and the impression you are constantly making. For training and true Linkedin education, seek out Lewis Howes.