All the websites I build are responsive, semantic and standards-compliant. Technical and on-page SEO is built in from the start. I routinely use modern styling techniques like Flexbox and CSS Grid.
Best practices to optimize speed, security and accessibility are a matter of course. I always include scheduled backups on WordPress sites and configure several 'hardening' settings.
I also routinely setup Google Analytics and Console on websites I build and provide a Data Studio report I've created.