Freelancing is the next best thing to being paid more for your full-time work, because professional work always pays more than unskilled. To find opportunities, let former colleagues or other personal connections that you’re available for freelance gigs. (Here are some ideas on how LinkedIn could be useful for that.) Or, post on marketplaces particular to your field. For instance, Mediabistro, a journalism site, allows freelancers to post profiles of their experience and services. Though these are more up to chance, designers can bid on jobs at or submit a design at Threadless, to see if it will be crowdfunded. Elance-Odesk also lists many freelance opportunities, and you can also post your own services on Fiverr, although some freelancers say these services create a race to the bottom on fees and so are not very lucrative. If you're new to freelancing, here's how to set your rates, and here's how to negotiate raises with clients.
 @Philip Taylor So by what you’re saying, I can be an unaccredited doctor or surgeon for someone (for example) but do it at a much lower rate than the accredited doctors and surgeons. Since I know what a scalpel is and I wear rubber gloves, I’m a doctor. So, I don’t have to have to respect the profession of medical science at all since I think I know what I’m doing and just go for it.

I recently stumbled on the Trim app and I have to say, this one is a game changer. It’s a simple app that acts as your own personal financial manager. Once you link your bank to the app, Trim analyzes your spending, finds subscriptions you need to cancel, negotiates your Comcast bill, finds you better car insurance, and more. And of course, the app is free! My bet is that it will only take a few days for Trim to put an extra $100 in your pocket. So easy!
Another way to generate passive income is to invest and be a silent partner in a business. This is very risky, but with risk comes the potential for high returns. For example, several years ago both Lyft and Uber were looking for private investors to invest in their companies. Today, they are worth billions - but you as an investor would only reap that benefit if they go public via an IPO, or get acquired. So, it's risky.
It’s something akin to picking stocks. You want to buy undervalued domains, and sell them later on at a higher price. For example, you can pick a domain that is out of favor, but could be related to some future event. So if you decide that the stock market is likely to crash in the future, you can buy a domain that includes the words stock market crash during a rising market, and then sell it in a falling market.
 @Philip Taylor The point is that this is design is specialized job and is not just a side job. Just because an individual may know a thing or two about the technical aspect of a program does not warrant them to fill that role as a designer. There’s more than just drawing a mark in a program. There’s strategy in brand development, marketing, etc… This is insulting to the creative industry to label logo and branding as a scheme to make extra money.
There are many ways to get people onto your list. Lead magnets are one such resource. For example, you can build ebooks, checklists and cheat sheets. But you can also do content upgrades, such as PDF versions of an article with added resources in them, four-part video training series, and more. Think about your audience and what you can offer them to better serve them, then treat them with some respect and you'll eventually reap the rewards.
If you're ready to enter the ecommerce fray, you could sell your own stuff. Of course, along with selling your own stuff on your own website comes a whole slew of both responsibilities and technical configuration and requirements. For starters, you'll need a website and a hosting account. You'll also need a merchant account like ones offered by Stripe or PayPal. Then you'll need to design that site, build a sales funnel, create a lead magnet and do some email marketing.

Writing an eBook, like you said, is not easy. First you have to have something to write about, which often means that you need to be some kind of respected expert in the field you wish to write about.However, if you can get past the initial trouble of selecting a topic, becoming an expert, and finally writing about that topic, that’s when the hard part really starts….
The appeal of these passive income sources is that you can diversify across many small investments, rather than in a handful of large ones. When you invest directly in real estate, you have to commit a lot of capital to individual projects. When you invest in these crowdfunded investments, you can spread your money across many uncorrelated real estate ventures so individual investments don't cause significant issues.
Using a food delivery service can’t necessarily earn you money, but it can help you save you money if you constantly find yourself throwing out half the food you buy. Food delivery services send a box of food every week with new, sometimes unique vegetables, meat, fruit, and so on. If you don’t have time to shop and want simple meal-prep that leads to a good meal, a food subscription service may be perfect for you.