Toy also urged Aussie employees to check their privacy settings and to consider making a private and professional account and keeping them both separate.
She also warned people against listing their workplace and role on Facebook, and said it might be wise to remove friends or followers who "might cause you trouble".
Another golden rule? Never "drink and post".
Toy said employers could take action against a worker over something that occurred outside of the workplace, including social media posts, if that conduct brought the employer into "disrepute", or if it was "incompatible with your duties" at work, or caused a significant breakdown in relationships.
"Be mindful that not everything is considered personal — it can be looked at as a public post, so if you post on platforms about your workplace you might run into difficulties in future," she said.
"Also be mindful of the fact that you can be dismissed for your conduct on social media even though that conduct may happen outside the workplace and outside of working hours."
Toy said it was essential for workers to check their organisation's social media policy.
"Most employers respect the increased prevalence of social media and have comprehensive social media policies about what's acceptable or not, so it's important to access that," she said.
She said while each matter needed to be considered individually, it was possible for someone to be sacked over a tweet or social media posts — and said workers needed to err on the side of caution.