Seo is Constantly Changing, Like all the time.
One of the hardest parts is knowing where to start with SEO, and that is where working with a marketing strategist is super important. If you are a business guru already then you are good.
For those of use that are not Marketing Masters, it is a good idea to a start talking to professionals.
Remember SEO changes all the time to make the search easier for the general user. One of the things Google has always focused on is quality content. So make good content for SEO.