There are many online tools that allow you to perform an SEO audit of your website. These audits will give you an overview of how well optimized your website is and if there are any issues that Google would see as a red flag. A couple tools that will give you some great insight to your website's SEO are SEMrush and Moz. Both of these SEO tools will give you an analysis of your website and alert you of any issues to fix. They are also great for researching keywords, tracking your rankings and seeing where your traffic is coming from. For more in depth SEO audits you could contact a marketing agency to identify which keywords you are currently ranking for and which keywords you should be targeting with your website.