Google recently updated the search quality rater's guidelines with this 160 page PDF doc and here we summarise the most important take aways.
1. Make sure your website is mobile friendly. If not you'll be seen as low quality in Google eyes and pay the price in search results
Probably the biggest takeaway from the Google guidelines is to make your site mobile-friendly (if it’s not already). By not doing this you are putting your website at a disadvantage and letting websites outrank you because they have mobile friendly sites - Google sees those with non-mobile-friendly pages as low-quality.
2. Make sure you content is useful to your readers
This one is obvious and if you're not creating content useful for your reader then why would Google rank you well in search results lets face it. Take a look at your supporting content across your website and review how it supports your main content. Adding related articles and linking to articles found on your own site is a simple way to provide additional value for the visitor. This will also help keep visitors longer on your website as they engage with your content, spend longer on the time.
3. Calm down with the advertising! monetise your site but not to the detriment of readers
We've all been on those websites, especially blogs, which are literally covered in ads - Google ads, affiliate ads, annoying pop up ads, in text ads and so on. As a blogger myself I can understand to a certain degree why many choose to monetise their site in this way but I would add a word of caution.
Find the right balance between monetisation and user experience. Look at your stats and see what is making you money as it's very common to find ads which are not generating any money and hence useless.
and finally, have these things in the back of your mind...
Make sure you provide sufficient information to a visitor, or a quality rater, that can answer simple questions about your site.
And don’t forget to include things like a simple contact form, that's just basics but I'm always baffled to come across sites in my link building research and outreach which don't have the simple things in place.
Your site should reflect E-A-T: