Pretty self-explanatory. You can start making money playing with dogs today using Rover. Rover lets you set your prices so you can charge fair rates for your services. In addition to walking, you can also offer doggy daycare, house sitting, and boarding through Rover. If you’d rather start your own thing, check out The Balance’s How to Start a Dog Walking Business.
As a course developer and promoter, I can say that on the face of of it, promoting can be easier than developing one. The upside of development though, is that once it’s done, have to do is keep it updated and it can earn you money for years. That’s the case with my SEO copywriter training course, which I’ve been teaching (and earning from) since 2009.
Be professional. When you submit a résumé, don’t type it in ALL CAPS and please don’t avoid the caps lock like the plague. Know how to use it without looking incompetent. Write in complete sentences with proper grammar. Of course, there will be exceptions, but even with the exceptions, you must keep it professional. You’re building their view of you.
The topic you choose must have enough depth that you can create a lot of content for it. This is important for building an authoritative site, for search engine optimization, and most importantly, for the end user. If you don't have enough content about a topic, you're not going to be taken very seriously as an authority on the topic and it's unlikely you can convince someone to make a purchase from you.