>>951984
>Do you think actively contributing/maintaining an open-source project is a good indicator for this?
If you can demonstrate your involvement, then yes. Write a journal, a blog or build your own website and use it as a professional portfolio. Explain what you're working on, why, how, and justify what you're doing.
If you're trying to appeal non-tech companies (administrative/office work), show that you master the tools they need, write scripts or design templates - and again, explain why, how, and justify what you're doing.
You have to stay active. Impose a deadline for each update and stick to it.
Every time someone tells you to be enthusiastic in your cover letter, they forget to add "when applicable"; if you're just going to mop the floor or fulfill some minor task, both you and your future boss are smart enough to know it is nobody's dream. Don't overdo the pandering. However, communicating on your work is a safer and more honest way to show your motivation.
If you have the opportunity to go to formations or seminars, do it. Try to meet people who could be interested in your skills (plenty of unskilled people sit through these things for the social aspect, in hope they meet "someone who knows how"), exchange ideas with others and see what advises they can give you.