While SEO is included in college-level digital marketing programs, the best way to learn is to teach yourself. Build a few free websites and practice as go, documenting each tactic and how it affected your ranking. In the end, you will not only get invaluable practice, you will have websites for your portfolio.
If there were free, informative instructions online that every website owner would do their own SEO, however, it is very time consuming. Many business owners would rather hire an expert so they can concentrate on their core business.
The Beginner's Guide to SEO from Moz is ideal for beginners. Google, the most popular website, the one that most SEO professionals focus on optimizing for, publishes an SEO Starter Guide, which you should study. Read online SEO magazines, such as Search Engine Land, as well.
Learn the basics about what makes a good domain name; you will need to buy several domains yourself to practice your craft and to eventually use in your portfolio. Start free blogs and websites in several different industries, so you will have a well-rounded portfolio. Practice adding META tags, adding tags to images and creating internal links until you are certain you have mastered your lessons.
Learn how to create informative, SEO-friendly content that is error-free; many SEO companies include content creation and content marketing as part of their services. If writing is not your forte, you can purchase original content online.
SEO Book's free Keyword Suggestion tool is invaluable as it lists the number of daily searchers for keywords on Google and Bing. As you become familiar with keyword research, you will want to invest in paid keyword tools.
Invest in a tool that checks robots.txt files to locate errors, although there are some free tools online that perform very well. A page load speed tool is also important since load speed affects a website's ranking.
SEO is evolving. Read the popular SEO websites to learn about Google's latest algorithm changes, which you must keep up with in order to call yourself an SEO expert. Without providing any bias, I might suggest checking in on 10 Best SEO's Best SEO Blog as a place to start!