Learn then selling guidelines. Each marketplace has guidelines that define what you can and cannot sell. State and federal laws also impact what items are prohibited. In general, you cannot sell alcohol, weapons, service contracts, animals or event tickets. Also, while not always prohibited, you may find restrictions on how you can sell items in some categories, such as art, gift cards and coupons. eBay, Craigslist and Amazon publish these guidelines on their websites.
Great list! I have another to consider that I personally have 35+ years experience providing. Clean up litter outside commercial properties on foot using inexpensive hand tools. It’s almost as easy to do as going for a walk! I started doing this as a side gig in 1981 and soon grew it into a profitable full-time business. I share my experience in my book, Cleanlots.
GoodFinancialCents.com has an advertising relationship with some of the offers included on this page. However, the rankings and listings of our reviews, tools and all other content are based on objective analysis. For more information, please check out our full disclaimer. GoodFinancialCents.com strives to keep its information accurate and up to date. The information in our reviews could be different from what you find when visiting a financial institution, service provider or a specific product's website. All products are presented without warranty.
Find a profitable niche. Starting with your interests, write down as many niche ideas as you can. Think about topics people might search online. Ideas include passions (like surfing or body building), fears (like spiders or speaking in front of crowds) and problems (like getting out of debt). Do keyword research to see it others are interested in the topic. Find out if a domain name is available that matches the keyword 100 percent. 
Our first overlooked opportunity is selling your knowledge. In this instance, we are talking about creating a course or eBook that you can make available for purchasing online. Because of the automation available today, you may be able to put in the work once when creating your packaged information and then enjoy those checks coming in for months or years to come.