Sure there are many things to review and get correct under these two broad categories.
Getting a good search listing is a marketing challenge. You will need to put yourself in the head of a potential customer or person who you would like to find your site. This is about putting your message, your thinking, your philosophy, your photos or your blog, out there so that other people can find it.
It is like being able to read the mind of your client at the precise moment they decide to buy what you sell.
Google has been called the database of intentions. At any given point, Google has a good idea of what humanity is thinking. Where is the first place you go when you need to research a topic, look up a definition, help someone with their math homework, or understand your EKG. “Hey Google! Where do I buy a _________?”
Conversion
Once you have the visitor on your page, the content of the page needs to help your client make a decision and ideally lead them to conversion. This means they ‘convert’ from a prospect to a client by registering, signing up, or making a purchase.
As part of an SEO service engagement, you want to ensure that your SEO agency is working on goals and measuring conversion success.
Part of the work of a good search engine optimization agency is to define and codify goals and then measure the success of these goals.