Definitely talk to your colleagues about babysitting/housesitting/ and pet sitting. A lot of the older staffers I’m sure have kids they are looking for responsible young adults to look after so they can go on a “date night” and especially as campaign season has arrived, there might be a lot more house sitting opportunities.
It’s a lot more flexible, you get paid under the table, and you tend to make more than you would at a soul-sucking retail job.
That said, few retail jobs would allow you to work one or two shifts a week. If you do decide to serve/retail, I say go for one where you’re not likely to spend any money – when I worked retail, I spent my entire paycheck back at the store because of my discount! (I worked at Anthropologie, my god, do I miss that discount!)