Creating a strategy is the single most important thing you can do. Where does SEO fit into your marketing plan? How do you measure it and what does success look like? Your strategy brings all of this together. From this you can create a smart tactical plan.
The two critical elements in building a website that helps search engines give you a good listing. Creating a logically structured website with the right use of keywords & phrases in the right HTML tags helps the algorithms index your pages.
The right type of authoritative links from outside your site and within your site builds confidence with the algorithms.
In a sense this is similar to on-site SEO but just more technical. Behind the human facing website is a technical world of site structure, web standards, responsiveness, compression, loading times and code, scripts and mark-up.
This is not just for developers but it is also important this is optimised for search algorithms.
A specific sub-set of searches that are vitally important if you have a physical premises and want people searching to find you. Optimising your website for local listings and building a consistent business details is critical.