Stand your ground if the kids misbehave. Be firm with the kids. If they try to tell you that their parents let them do something that the parents specifically said not to do (like stay up past their bedtime), err on the side of caution and obey the parents’ rules. The parents will be impressed by your maturity and responsibility and hopefully invite you back!
If you have a propensity for writing and you can slay with your prose, consider writing an ebook. While the market has certainly become saturated as of late, books that help teach people about a technical topic still sell extremely well. This is a great source of passive income but does require a large amount of effort at the outset before any money is generated.
Etsy: While Etsy's popularity has declined recently, it's still a great resource for selling handmade items online. No need for complex ecommerce sites or merchant accounts or any sort of automation. The company takes a commission of every sale and charges a small listing fee per item. But many still use Etsy as their primary source of income. The best part is that you can also sell digital products on here such as poster designs.
When you lack the luxury of time, making money on or offline can seem like an impossible task. How are you supposed to do that when you're working at a life-sucking nine-to-five job? While the stability of full-time employment might allow most to sleep well at night, it doesn't empower your creative juices to search for new income-producing strategies.
The ego is the driver making the decisions. It decides between the devil (the id) and the angel (the super-ego) on either shoulder (yes, all those cartoons you've ever seen are partly true). We have voices in our mind, and it's up to the ego to decide which one to fulfill. Its goal is to satisfy the id in some way while also attending to the super-ego.
Amazon has spent years perfecting the art of online selling and you’ll learn a lot about online marketing by observing how they do it. They constantly test different ways of promoting products and have evolved their site quite a lot over the years. See what widgets they use to promote related products, watch how they use reader reviews, and see the way that they describe products.