Lowering expectations is one way to have a merry Christmas this year, which may mean focusing on the relationships that actually bring us joy.

Australians are also being reminded to look out for others these holidays, asking those without plans to join the festivities, however small or large.

Clinical psychologist Rachael Murrihy, director of the University of Technology Sydney's Kidman Centre, said many people buy into the myth that Christmas is a "Hallmark card" experience.

"The number-one piece of advice I give is to manage your expectations," she told AAP.

Family conflicts and tensions often play out, and with the addition of alcohol seemingly innocuous interactions can trigger a fight-or-flight response.

"You might have a sister interrupting a story that you're telling or a mother that criticises your cooking," Dr Murrihy said.

"And that ties into the fact that you grew up with a sister who never listened to you or a mother who was highly critical."

Unsolicited advice can be another point of tension, like asking when the grandkids are coming or commenting on a person's weight.

Ian Hickie from the University of Sydney's Brain and Mind Centre gives people permission to ditch the family Christmas altogether if all it brings is angst.

"Be more realistic with family, you don't necessarily have to try and please everyone through the whole period," Professor Hickie said.

"In fact you'd be better off focusing on the relationships that really do work rather than trying to solve problems that have never been solved.

"I give people permission not to go to the family Christmas. For God's sake, spend time with friends and others you really do like and relax with, and choose to be with."

Christmas is a time when we tend to reflect, which can lead us to feelings of loneliness, clinical psychologist Michelle Lim said.

Dr Lim, who is scientific chair of the Ending Loneliness Together network, said those experiencing loneliness can take small steps to improve their state of mind.

These include striking up a conversation with their barista or building on neighbourly connections to say more than "hi and bye".

"We don't have to go out there to make new friends right away. Those sorts of little things make a difference," she said.

Joanne Winwood, a loneliness advocate from Feros Care, urged Australians to reach out to those who might be isolated over the holidays, particularly the elderly.

"Our campaign's called 'the more, the merrier' because the more you do for others at Christmas the merrier your Christmas will be," she said.

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