In my experience upgrading clients' LinkedIn profiles and resumes, one critical item is often out of date or missing entirely. Volunteer work.

If you don't have a volunteer section on your professional profile and resume, you should -- assuming you have volunteer experience. (If you don't, you should get some. But that's another story.)

Eight out of 10 "hiring influencers" say they believe active volunteers move into leadership roles more easily than non-volunteers, according to the 2016 Deloitte Impact Study. Nearly nine out of 10 say job seekers who include volunteerism are more competitive. But only one in three resumes actually lists volunteerism. I can attest that this is often this is often the case with LinkedIn, too.

"Showcasing your volunteer experience on LinkedIn can demonstrate that your commitment to the community is an important and productive one," says Doug Marshall, managing director, Corporate Citizenship, Deloitte Services LP.

Here are three tips for adding your volunteer work to your LinkedIn and resume.

1. Treat it like a job.

Do more than just list your volunteer experience a single bullet point. Think details. In the volunteer sections of your Linked and resume, describe your experience as your regular work. Include dates of service, title, responsibilities and accomplishments. What skills did you bring? How did you lead? What did you learn or achieve? Remember to include internal volunteer experience -- that is work that you did from within your company. Did you organize your work team's Habitat for Humanity service day, for example? 

2. Include it in your cover letter and LinkedIn summary.

You can further highlight your volunteer work by mentioning it in your cover letter and your LinkedIn summary story. Here is your chance to talk about what has drawn you to the organizations for which you've given your time. If a work culture that encourages volunteering and gives staffers time to do it is important to you, this is another reason to underscore that it's important to you too.

I once had a phone interview in which the hiring manager laughed at one of my volunteer entries and then informed me that at his firm I'd have to take time off work to volunteer. I'd never expected the firm to give me time off to volunteer, though other organizations I've worked for have; it was the laugh that left me cold. We didn't speak again, and I was OK with that.

3. Look to your volunteer gigs for referrals.

When you're thinking of people to ask to be phone references or write a LinkedIn recommendation, keep those you've served with in mind, too. This could be especially helpful if you are looking to change lines of work. If you want to move into a finance job and your only experience is serving as Treasurer of a nonprofit board -- well, that is excellent experience to highlight and get others to endorse.

Bottom line: You volunteer because it makes you feel good to do good. You list it on your resume and LinkedIn to be competitive and to also land in an organization in which the workplace culture aligns with your values.