In the midst of the recession, many job seekers have spent more time on LinkedIn to connect with colleagues, customers and partners in an effort to land a new gig. Unfortunately, many people commit common errors in their LinkedIn profiles that cost them new opportunities, says Jason Alba, CEO of JibberJobber, a company that provides web-based tools for managing your job search.

Alba, who recently released a DVD called LinkedIn for Job Seekers, shared with CIO.com the six most common mistakes he sees on LinkedIn profiles. Here's how to spot trouble in your profile and fix it.

1. Don't Get in Picture Trouble

Many people choose not to use a picture on their LinkedIn profiles. While some of you have your reasons, it's a mistake for the typical user, Alba says. Some common concerns: Perhaps you don't want to disclose your ethnicity, or you don't consider yourself photogenic.

"Some situations are justified in not using a profile picture, but in the end I encourage people to include one because it shows you're comfortable with yourself," Alba says. "It also makes your profile a lot more personable."

Alba recommends a professional headshot for LinkedIn, rather than the picture of you in front of a mountain or lake that you utilize on Facebook. In addition, if you're a job seeker, odds are that you will meet your prospective employer in a face-to-face interview, so that picture of you twenty years ago that you like to leave up there — that needs to be replaced.

"Sometimes people are floored when they see the person if they left a really old picture up there," Alba says.

2. Write a Descriptive Professional Headline

When you edit your LinkedIn profile, you have what Alba calls a "professional headline" right beneath the name. The common mistake here (as shown in the picture below) is to simply put your name and title. He believes you should use something catchier. Instead of saying, "project manager for X company," say something more specific: "I manage complex projects involving IT and marketing."

When people search for you, they will see this professional tagline, and it might decide whether or not they feel compelled to click on your name and see your profile, Alba says.

"Think of yourself as a marketer, and this is where your big ad appears to the world," Alba says.

3. Properly Label Websites Displaying Your Work or Blog

LinkedIn offers you the ability to list the websites where your work might be displayed. This is a great option if you keep a personal website with a resume or a blog. But when you go to edit the website descriptions, Alba recommends dispensing with LinkedIn's default descriptions of "my website" or "my company." Those descriptions aren't a compelling read for employers, he says.

Instead, when you edit your "websites" section, LinkedIn provides a drop down menu (see picture below). Click "other," and you can upload the link and describe it as you see fit. Instead of "my blog," you might write, "my blog on complex project management."

4. Consider a Vanity URL

Maybe you haven't changed the default URL that LinkedIn provides for your profile. Especially if you have a common name, this will make your name after the LinkedIn address appear with a bunch of ugly code and numbers. If you have to give your LinkedIn profile address over the phone, or you wish to print it on your business card, it should be as concise and self-explanatory as possible, Alba says.

"It literally takes 30 seconds, and it makes your profile look more on purpose," Alba says.

(When you edit your LinkedIn profile, go to the "public profile" section to create your LinkedIn URL of choice).

5. Finish with a Strong, SEO-Friendly Summary

The "summary" section of your LinkedIn profile could be the biggest missed opportunity for the majority of job seekers, Alba says. While this section has a 2,000 character limit, Alba suggests packing as much about you and your abilities into it as possible.

In reality, the ability for people to find you will depend on LinkedIn's search engine linking your name to certain search keywords. So (staying with our repeated example), a project manager might want the term "project management" to appear a few times throughout the summary.

"Most summaries are a couple sentences or a couple paragraphs, and they're missing out," Alba says. "The more you put in the summary, the better your SEO is."

Remember that you're in a crowded field of applicants. Alba recommends that you put in short "problem, action and results" stories that show how you contended with challenges that helped your business succeed.