I am new to this and I’m struggling to get my site found. What are the most important things I should be doing on each of my pages
Hello Sheen, we all have to be a newbie at some point 
For google shopping, and namely free listings, it’s extremely difficult to get found. It’s so difficult that I would not recommend focusing too much on this.
But the first thing you need to do is ensure that your data feed quality is optimized by following the requirements and recommendations here: https://support.google.com/merchants/answer/7052112
Then for the pages itself, check your Google Search Console data to see if the relevant search terms are getting triggered, if not, then write more / improve your content to highlight these keywords. But please note, SEO is very difficult. You might find that advertising is a lot easier compared to SEO.