I think by now, most of the principles of SEO are more or less well understood by people that have done their time in the trenches since 1999, although new platforms and data types arrive all the time keeping the need for ongoing practice or testing even more important than in the past. The need to learn about new entrants like Siri, Alexa, Facebook, Linkedin, and specialist search engines (like Booking.com, for example) will keep SEOs on their toes for years to come.
Baseline ranking assessment. You need to understand where you are now in order to accurately assess your future rankings. Keep a simple Excel sheet to start the process. Check weekly to begin. As you get more comfortable, check every 30 to 45 days. You should see improvements in website traffic, a key indicator of progress for your keywords. Some optimizers will say that rankings are dead. Yes, traffic and conversions are more important, but we use rankings as an indicator.
Competitor Backlink Audit: Analyze the link profile of your competitors and look for opportunities that can help improve your own link building and search performance. Whenever you perform a competitor backlink check or audit, you must also check the inbound links that are pointing to top ranking pages so you wouldn’t miss out on important link opportunities.