For well-established websites, the way to improve is to look at micro-moments and understand where the potential to improves lies. Looking at the shopping funnel will show you where the areas with the biggest issues lie.
Use this report to find out where you should concentrate your efforts. Look at the orange bar. See where is the biggest drop-off in the completion rate. In the above example, you can see that only 28.90% of the website users see the Product Page. Increasing the traffic to the product page will automatically increase the conversion rate which is lower in the funnel.
Think about strategies to drive more traffic to product pages, or if you have an issue with the third conversion step (Users that Add to cart items) about strategies how to convince users to add more items to the basket.
This report is meant to help you reduce the noise and help you share light on a big area you should focus if you want to improve your conversion rate.
After you implement the changes required for your step come back in a week time and see how last week (after the change) compares with the previous week (the week with the old layout). You can now see comparing the grey and the orange bar and see if your change was for the better or worst.