How does one go about getting/keeping two jobs?

I currently work part-time (about 20hrs/week) at a retail store. I like it there, but lately I've been thinking I'd love to try something new, to get a little extra money and some variety in life. I've been considering getting a part-time job at Starbucks as a barista. I don't want to leave my current position. So I'm wondering how people manage to work two part-time jobs without any scheduling conflicts. Is there anyone who has experience with this? What are the dirty details? I'm starting from 0 here! Thanks!!

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