Should you ever notice somebody staring at you on public transport, it's perhaps worth checking that it isn't cartoonist Wendy MacNaughton sketching your likeness.

That’s where the artist and illustrator goes when she needs some inspiration. ‘I love to eavesdrop,’ she says from her sunny home in San Francisco. ‘The subway is the best place to watch people and notice little things. I’m an obsessive observer of everything, and I find some of my best subjects when I’m on my daily commute.’

MacNaughton's sketches are detailed and intricate. Though light-hearted and charming, her illustrations are inquisitive and psychological – each piece is a vignette or extended metaphor, and they often have a storybook quality to them.

‘The most important lesson I’ve learned was from my grandmother,’ she explains. ‘The details tell the story and the most interesting stories are those that are overlooked.’

MacNaughton’s overlooked arcs, a sort of latterday faits divers, draw on all walks of life. From public library workers to winemakers and chess players, via a story about a lost cat, when she decides to sketch a particular person MacNaughton devotes months to it – to watching them, to drawing and writing about them, and to publishing long illustrated narratives on what they mean to her.

‘I think of my work as like a ‘compound’,’ she reasons, when asked about the social message behind her drawings. ‘That sounds very science-y, but it basically boils down to the fact that neither my illustrations nor my words work without the other. When I quit my job in advertising it was to do something more meaningful with my life. Now I get to do something I love – seriously, this is my dream job – but I also have the opportunity to show people things they don’t necessarily think about.’

She’s been fairly successful with this venture too. When she took up illustration again after a sejour between school and adulthood, it was to help to create an education campaign for Rwanda’s first democratic local elections. MacNaughton’s work has since been featured in the New York Times and Time Out, and she has just finished illustrating a book, Lost Cat: A True Story of Love, Desperation and GPS Technology, with her partner, Caroline Paul.

‘Drawing lets me work through lots of my neuroses. It’s kind of like my meditation,’ she muses, in her laidback San Franciscan drawl. Anything is fair game in her illustrations and that’s perhaps why you’ll most often find her on the ‘subway’ watching and listening to people, and then scribbling it all down in her notebook.