On smiling more

In the space of a few days, I was told by people from different walks of life – my mum, a random French shopkeeper, a couple of friends – that I should smile more.
The thing is, often I’m not feeling unhappy but my default expression is a 😐 not a :-> and I don’t realise it.
Last night I was Twittering about how a local gal in French class was annoying me by pouncing on my every mistake. She’d go ‘Harh?!” when I asked a question or said something not quite right, even though she herself wasn’t that good in French either. She would also chat to the Brit guy beside her but not turn to talk to me. There are only 3 of us in the class.
In the light of the weekend’s feedback on my demeanour, I thought I could do a couple of things (apart from punch her in the face, which @dominik recommended :).
I could work harder on my French so that I’d make less mistakes and we’d learn from each other instead of pointing out each other’s faults.
Next, I could smile more and make the effort to talk to her, as much as I initially thought she was one of those who were nicer to expats than to their own kind. But we tend to stereotype each other when we have bad first impressions. Maybe she assumed I was unfriendly because of my serious face, and I classified her as a snob when she ignored me.
As it was, it was our second lesson together today and it was much more enjoyable because we actually loosened up more and found out more about each other. Somehow my French had also improved and the vocabulary I picked up 11 years ago was coming back, so I could enhance the sentences we were learning to make. We left, feeling positive about our lesson and looking forward to tomorrow.