That's probably not super helpful, but one of the best ways to get experience is to get hands on practice.
Sign up for a development instance: https://developer.atlassian.com/blog/2016/04/cloud-ecosystem-dev-env/ You can play around in cloud to get a feel for creating workflows, screens, custom fields ect.
Use amps standalone environments: https://developer.atlassian.com/server/framework/atlassian-sdk/install-the-atlassian-sdk-on-a-linux-or-mac-system/ These will give you a similar experience to a server environment, but locally on your machine.
Watch training and attend AUG meetings: Atlassian has documentation for Jira. You can find online training. You can attend user groups to see how people are using the Atlassian tools.
Consider taking the ACP exams to force yourself to learn and improve.
Above all immerse yourself in the tools. Anyone can learn to administrate quickly and well.
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