It's convincing shop assistants that she's old enough to buy painkillers that can sometimes prove more taxing.
"I'm 27 in real life, but I'm blessed with looking quite young," says the RSAMD graduate.
"I got asked for ID buying paracetamol a couple of months ago. I get ID'd for alcohol all the time.
"It's great - I am quite used to playing younger characters."
The Thurso-born actress draws on her youthful looks in making her debut this week at Oran Mor's lunchtime theatre series, A Play, A Pie, And A Pint.
Having trod the boards of theatres in every Scottish city since she graduated in 2009, she has found that the intensive two-week rehearsal period has meant going back to the homework of her school days.
"You really have to up your game," she said.
"In a normal rehearsal period, the first two weeks are very much about discovering things and you're not worrying too much about learning your lines.
"But with this, right from day one, I've really had to go home at night and really work at it."
Helen takes to Oran Mor's basement stage for the first time in 3 Seconds, a co-production with Edinburgh's Traverse Theatre written by actress and journalist Lesley Hart, who won Playwright Studio Scotland's New Playwright Award in 2011.
The play, which transfers to Edinburgh after a week-long run in Glasgow, is directed by the Traverse's associate director Hamish Pirie.
Helen's character is a foul-mouthed 14-year-old called Christine, whose mother Diane is played by actress Claire Knight, better known as River City's Iona.
"The thing I have to remember is teenagers' energy is very different," said Helen, who portrayed a teenager who claimed her pregnancy was a gift from God in BBC Radio 4 play Immaculate.
"Teenagers just sometimes go off on one - they're 10 seconds ahead of themselves. They go at quite a speed.
"Sometimes they don't think they just say it or do it and they have to deal with the consequences afterwards."
Both mother and daughter are born and bred in a fictional town in the north of Scotland.
When their small community is hit by a flood, a soaking, bloody newcomer to the area (played by Cara Kelly) arrives at the door and the three females are forced to confront a fleeting yet divisive moment – lasting three seconds – that happened six months before.
"They're all trapped right now because of this event," said Helen.
"They all need answers.
"This flood has brought them together to see if they can find the answers, to see if they can move on, or if they're going to be stuck within this place.
"Even although three seconds is a really short time, it's an eternity for these people."
The idea of an incomer to a small Scottish town is something with which Helen readily identifies, thanks to her Caithness upbringing.
"It's a wonderful place to come from - that sense of community is a wonderful thing," said Helen, who worked in a call centre before finally securing a place at RSAMD.
"But also, on the flip side of it, it's a bit like everybody knows everybody else's business, and if you come into that community, as much as people will accept you, you will always be known as an incomer, someone who is not from here.
"No matter how long you live there for, if you weren't born and bred and your family can't be traced back, then you will always be from the outside, ever so slightly."
After years spent auditioning for drama school, Helen modestly claims to being "lucky" for the few gaps in her CV since graduation.
She has won acclaim playing a young Lady Macbeth to CBeebies' Raven star James Mackenzie's Macbeth in a tour with Open Book theatre company.
The actress has adapted to the light relief of panto at Edinburgh's Royal Lyceum in The Snow Queen as well as meatier roles in the National Theatre of Scotland's award-winning co-production of Peer Gynt with Dundee Rep.
But it was in recording a BBC radio drama at the Maida Vale Studios in London that she got her biggest brush with fame so far - featuring in a play, The Quest of Donal Q, alongside Billy Connolly and Brian Cox.
"That was probably one of the best days of my life," said Helen.
"It was just one of those days that you think if I don't work again, at least I've always got this memory of standing at a microphone next to Billy Connolly.
"It was worth all the years of trying to get into drama school. That day made it all worthwhile."
Having enjoyed her experiences of radio work, her goal for the next 12 months is to secure her first TV or film role.
"I've been lucky to always know where my next theatre job is coming from," she said.
"I think I've had only two TV auditions my whole time out.
"TV is a completely different skill, so I'd be really keen just to start learning about that."
The Evening Times is media partner of A Play, A Pie And A Pint, which was recently named 'Producer of the Year' in the Stage 100 Awards, the annual awards from the UK theatre industry's weekly newspaper.
The 18th season runs until June and includes new work by Glasgow crime novelist Denise Mina, father and son playwrights Dave and Davey Anderson, Scots makar Liz Lochhead and plays by three writers from China.
l3 Seconds is at Oran Mor, Byres Road, until Saturday, doors open at noon. Tickets from £8 available on the door or www.ticketweb.co.uk