I would invest time in contributing meaningfully to (existing, well known) Open Source projects for the sake of building something cool or fixing something inte

I would invest time in contributing meaningfully to (existing, well known) Open Source projects for the sake of building something cool or fixing something interesting. I've worked with people who had very little professional experience but had done enough OSS that I knew they were both competent and great at working with other people, as well as not needing to have their hand held. I'm sure my opinion isn't universally held, but if I see good sized contributions from someone with very little professional experience, I consider them head and shoulders above other juniors and would consider them mid level.