Checkout Optimization: from 35% to 48% completion rate

The rate of starting-to-completing the checkout was ≈35%:

Some of the reasons were:

website timeouts due to exceeded RAM limit on the shared hosting

different PHP errors

the checkout page was using the new Woocommerce checkout block which wasn't compatible with GLS shipping and BoxNow delivery plugins

After I made the following changes:

migrated the website to a VPS hosting

fixed bunch of PHP errors by applying theme and plugins updates, clearing transients

rebuilt the checkout using the traditional Woocommerce shortcode (to ensure compatibility with the GLS shipping and BoxNow delivery plugins)

changed the "Place order" button color from red to a shade of green

removed "Subscribe to our newsletter" section from the checkout page

added FAQ section to the checkout page

optimized the website for performance

enabled cash on delivery payment method

the rate for the same period (20 days) became ≈48%:

This is an absolute increase by 13 percentage points (from 35% to 48%).

And a relative increase by ≈37% ( (48-35)/35 ≈ 0,3714 ).

Unfortunately, the client hadn't had a budget to solve all tech issues so the final result could be better. But still, it's an improvement.