It's very easy to make mistakes on your LinkedIn profile. These days, you need to consider how each section of your profile is being perceived. The photo, headline, summary, and work history sections must all be optimized for maximum effect. Getting someone to notice your profile is hard enough. Putting something on the profile that makes them say, "no thank you" before they've even finished reading it is what you're trying to avoid.
The word "summary," by definition, means short.
It's bad enough some LinkedIn users make the rookie mistake of writing their profile in the third person. What's even worse is when they write an epic novel in the section that, by definition, is supposed to be short. Your summary isn't a place for you to go on and on about how great you are. It also isn't the place for you to detail exactly what you want in your next employer. Instead, it should effectively showcase your professional skills and accomplishments in a way that motivates readers to scroll down and learn more about you.
When it comes to your LinkedIn summary, white space is your friend.
In marketing, there's a concept of using white space as a way to draw a reader's eye into the thing they want them to understand most. White space is a very effective tool to use on a LinkedIn summary. Instead of long-winded paragraphs that make the reader feel like you are desperately trying to sell them snake oil, creating a two- or three-sentence summary and then a vertical list of key skill sets can literally get the reader to scroll down and read more of your profile.
To see how white space works, imagine you're a project manager. Your summary might look like this:
15+ years in project management. I've worked in the financial and health care industries, leading projects ranging in budget size of $5,000 to $1.2M. I have coordinated the efforts of project teams with as little as 3 to as many as 24 stakeholders. My skills include:
Reporting & Budgeting
Staff Training & Development
Project Timelines & Delivery Schedules
Full Project Lifecycle Management
In the case of your LinkedIn summary, less is more. By keeping it factual and concise, you give the reader just enough information to make them want to learn more, letting their eyes be drawn to the skills and experience you want them to notice most. Whereas, when you get overly wordy or creative with a long-form summary, you create information overkill, which is more likely to make the person think you aren't a fit for what they need.
P.S. In your summary, numbers are worth a thousand words.
One other technique that's important to incorporate into your LinkedIn profile, especially in the summary, is the use of numbers. The human eye can read and process numbers faster and more easily than it can words. Numbers are symbols, which are also pictures. As they say, "a picture is worth a thousand words." By adding numbers, you're quantifying your experience in a way that makes it easier for hiring managers to understand the depth of your experience. It also provides a sense of credibility because they can determine if the numbers sound accurate and reasonable. Numbers prove the experience you claim to have is real. And that can help you get the interview!