By screwing up, owning it, and fixing it. It's impossible to get real operational knowledge without actually working on it. If you're in school, design competitions are awesome. If you're working in IT already, take responsibility for some processes.

I would suggest a combination of being a point person to solve production issues (either on a pager or being a developer who fixes problems after an outage), or a more involved side project (try keeping Wordpress running on a VM when something is on HN, etc)