Confirming everything works before you stop thinking about it.
THE BROWSER CHECKS
Visit all four forms in a private window: with and without www, http and https. Each should reach your canonical form with a padlock.
Click the padlock and view the certificate: correct hostname, trusted issuer, valid dates.
Open the developer console and confirm no mixed content warnings on the homepage and on an inner page.
THE ONLINE CHECKS
An SSL testing tool reports the certificate chain, supported TLS versions, and configuration weaknesses, with a grade. A redirect checker confirms a single hop from each starting form.
THE PAGES TO TEST
Homepage An inner page with images A contact form Checkout, if you run a shop The admin login
WHY THE INNER PAGES MATTER
Mixed content frequently affects older content with embedded images while the homepage is clean. Testing only the homepage misses it.
ON MOBILE
Test on a phone as well. Mobile browsers are stricter about certificate chains than desktop ones.