It's the day after the night before. You're on Facebook and a notification appears - a friend has uploaded photos of you looking worse for wear.

It's embarrassing, but what harm - the only people who care are friends, right? Wrong - employers are watching too and they want to find out how you're portraying yourself online.

A survey released in June by international employment website CareerBuilder showed 39% of employers are using Facebook to research job-seekers, with 43% finding something to stop them from hiring.

Half this group discovered inappropriate photos and references to alcohol or drug use, while others saw candidates bad-mouthing former employers, making anti-social remarks, or lying about qualifications.

On the other hand, the survey showed that some company managers formed a positive view of potential employees after viewing their online profiles, with 19% saying they found a reason to hire a person.

Social media consultant Lorna Sixsmith tells Irish Country Living that younger people need to be conscious of what they are putting on the internet.

"It's a huge issue for students and graduates, because many of them don't realise that it's not just their friends looking at their Facebook and Twitter pages," she says. "At the age of 17 no one thinks about what kind of damage their status updates or tweets can do, but they are on the internet for all to see unless you make your page private."

It is possible to make your own Facebook page completely private to make sure that people you're not connected with cannot view your photos and status updates, but that won't prevent photos of you appearing on your friends' profiles.

"Even if your page is private, your information can be visible on friends' profiles. People should be aware of anything that is being posted about them on Facebook," says Lorna.

"It is possible to tailor privacy settings to ensure people ask permission before tagging a photo of you," she adds. "And you shouldn't be afraid to ask a friend to delete any inappropriate images or posts related to you."

Twitter users also need to be careful about what they're posting.

"Sometimes people get into conversations that are not appropriate on Twitter," says Lorna. "Also, people do not tend to make their tweets private."

However, unlike Facebook, Twitter can be used to create a positive public image, particularly for those working in journalism, marketing, public relations or business.

"Make sure you emphasise what you do," advises Lorna. "For example, if you're training to become a journalist, tweet about articles you're reading and engage in intelligent conversations with other media professionals.

"You should think about your bio too. State your qualifications and whether you're looking for a job. You never know who is looking and who might be able to employ you."

Many people fall into a habit of narrating their day through Twitter, but Lorna says you need to be smart about what you tweet.

"Don't just talk about your personal life but show you have a good work ethic by tweeting about whatever activities you're engaged in, even if it's voluntary work," she adds. "Don't tweet too much though - employers will think you spend all day online."

LinkedIn, which can be described as an online CV, is used by recruitment agencies and companies to headhunt for employees. Unlike Facebook and Twitter, it is not used socially but can be a highly effective tool for jobseekers.

"LinkedIn is important. You can connect with employers at home and abroad and, if used effectively, you could end up with a job anywhere in the world," says Lorna.

After registering with LinkedIn, you will be presented with connections based on your email contacts. Once your profile is updated with relevant skills and expertise, LinkedIn recommend people and groups that could be of interest. You can also ask former employees for references which can be read by the public.

do better

"You should include all your skills, achievements and work experience in your profile, even if you consider them to be insignificant. Look at your peers' pages and see what they're doing, and find out how you can do better," continues Lorna.

Social media can impact job prospects in different ways, depending on how you present yourself. Maybe leave the camera at home before your next night on the town ... or ban your friends from posting the evidence online.