Email Marketing: Email marketing is still one of the most effective digital marketing channels. Many people confuse email marketing with spam email messages we all receive per day, but that’s not what email marketing is all about. Email marketing is the medium to get in touch with your potential customers or the people interested in your brand. Many digital marketers use all other digital marketing channels to add leads to their email lists and then, through email marketing, they create customer acquisition funnels to turn those leads into customers.
Website saturation and popularity, or how much presence a website has on search engines, can be analyzed through the number of pages of the site that are indexed by search engines (saturation) and how many backlinks the site has (popularity). It requires pages to contain keywords people are looking for and ensure that they rank high enough in search engine rankings. Most search engines include some form of link popularity in their ranking algorithms. The following are major tools measuring various aspects of saturation and link popularity: Link Popularity, Top 10 Google Analysis, and Marketleap's Link Popularity and Search Engine Saturation.
Facebook pages are far more detailed than Twitter accounts. They allow a product to provide videos, photos, longer descriptions, and testimonials where followers can comment on the product pages for others to see. Facebook can link back to the product's Twitter page, as well as send out event reminders. As of May 2015, 93% of businesses marketers use Facebook to promote their brand. A study from 2011 attributed 84% of "engagement" or clicks and likes that link back to Facebook advertising. By 2014, Facebook had restricted the content published from business and brand pages. Adjustments in Facebook algorithms have reduced the audience for non-paying business pages (that have at least 500,000 "Likes") from 16% in 2012 down to 2% in February 2014. 
I would focus on building your personal brand online and building a website right away that you can use as a testing ground for learning digital marketing skills. Most digital marketing programs are too theoretical and digital marketing is a fast evolving industries so you need to be constantly learning through active experimentation to become good enough to consistently make money.
Small businesses also use social networking sites to develop their own market research on new products and services. By encouraging their customers to give feedback on new product ideas, businesses can gain valuable insights on whether a product may be accepted by their target market enough to merit full production, or not. In addition, customers will feel the company has engaged them in the process of co-creation—the process in which the business uses customer feedback to create or modify a product or service the filling a need of the target market. Such feedback can present in various forms, such as surveys, contests, polls, etc.
Pay-Per-Click (PPC) Advertising: PPC advertising enables you to reach internet users on a number of digital platforms through paid ads. You can setup PPC campaigns on Google, Bing, Linkendin, Twitter, Pinterest, or Facebook and show your ads to people searching for terms related to your products or services. PPC campaigns can segment users based on their demographic characteristics (age, gender etc) or even their particular interests or location. The most popular PPC platforms are Google Ads and Facebook.