For example, to implement PPC using Google AdWords, you'll bid against other companies in your industry to appear at the top of Google's search results for keywords associated with your business. Depending on the competitiveness of the keyword, this can be reasonably affordable, or extremely expensive, which is why it's a good idea to focus building your organic reach, too.
As for what should your sandbox be, you have a few options. The easiest is to start a blog. That’s what this site was started as: a sandbox for learning content marketing, and it only became my full-time job on accident. A blog is a perfect sandbox for learning digital marketing since you can test almost all of the tactics on it, it’s low-cost, and you’ll improve your writing in the process.
One of the smartest decisions that I ever made was to skip the MBA and go straight into my marketing career. From the hands-on experience by leading marketing teams and all the marketing books, podcasts, and blog posts I’ve consumed over the years, I’ve basically given myself an MBA in marketing at a fraction of the cost. And I got paid along the way.
Search engines want to help you succeed. In fact, Google even has a Search Engine Optimization Starter Guide, much like the Beginner’s Guide! They're also quite supportive of efforts by the SEO community. Digital marketing conferences — such as Unbounce, MNsearch, SearchLove, and Moz's own MozCon — regularly attract engineers and representatives from major search engines.
If you do decide to go with a blog though, please, for all of our sakes, do not start a marketing blog. The Internet is littered with unhelpful marketing blogs by novice marketers. Starting one will be discouraging to you since it’ll be much harder to get traffic, and you’ll be writing about things you know nothing about, so please, don’t start a marketing blog.